1
Sami Heistaro
TRENDS AND DETERMINANTS OF
SUBJECTIVE HEALTH
Analyses from the national FINRISK surveys.
ACADEMIC DISSERTATION
To be presented with the permission of the Faculty of Medicine,University of Helsinki, for public examination
in Auditorium 1, Biomedicum, Haartmaninkatu 8, Helsinkion Saturday 16th November, 2002, at 10 o’clock
National Public Health InstituteHelsinki, Finland
and
Department of Public HealthUniversity of Helsinki, Finland
Helsinki 2002
2
Copyright National Public Health Institute
Julkaisija – Utgivare – Publisher
Kansanterveyslaitos (KTL)Mannerheimintie 16600300 HelsinkiPuh. vaihde (09) 47441, telefax (09) 4744 8408
FolkhälsoinstitutetMannerheimvägen 16600300 HelsingforsTel. växel (09) 47441, telefax (09) 4744 8408
National Public Health InstituteMannerheimintie 166FIN-00300 Helsinki, FinlandTelephone +358 9 47441, telefax +358 9 4744 8408
ISBN 951-740-314-3ISBN 951-740-315-1 (PDF Version)ISSN 0359-3584ISSN 1458-6290 (Online Version)
Hakapaino OyHelsinki 2002
3
Supervised by
Director Pekka Puska, MD, PhD, MPolScNoncommunicable Disease Prevention and Health Promotion
World Health Organization, Geneva, Switzerland
and
Professor Erkki Vartiainen, MD, PhDDepartment of Epidemiology and Health PromotionNational Public Health Institute, Helsinki, Finland
Reviewed by
Docent Ossi Rahkonen, PhDDepartment of Social Policy
University of Helsinki, Finland
and
Professor Jussi Kauhanen, MD, PhDDepartment of Public Health and General Practice
University of Kuopio, Finland
Opponent
Professor Marja Jylhä, MD, PhDTampere School of Public HealthUniversity of Tampere, Finland
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CONTENTS
LIST OF ORIGINAL PUBLICATIONS 6
1. ABSTRACT 7
2. INTRODUCTION 9
3. LITERATURE REVIEW 13
3.1 Self-reports on health 13
3.2 Socioeconomic factors and health 13
3.3 Self-rated health 15
3.4 Back pain and other symptoms 17
3.5 The health of the inhabitants of Russian Karelia, a region
which borders Finland 19
4. AIMS OF THE STUDY 21
5. MATERIALS AND METHODS 23
5.1 The FINRISK surveys 23
5.2 Samples 23
5.3 Methods of collecting data 24
5.4 Statistical methods and data analysis 26
5.5 Further analyses in the results section 26
5
6. RESULTS 29
6.1 Trends in self-rated health (Article I) 29
6.2 Trends of back pain (Article II) 30
6.3 North Karelia and Pitkäranta (Article III) 32
6.4 Self-rated health and mortality (Article IV) 33
6.5 Further analyses 35
7. DISCUSSION 41
7.1 Comments on the materials and methods used in this work 42
7.2 General developments of health in Finland 44
7.3 Health and socioeconomic background 45
7.4 Self-rated health and its association with mortality 46
7.5 Back pain 48
7.6 Comparing North Karelia and Pitkäranta 49
8. CONCLUSIONS 51
9. ACKNOWLEDGEMENTS 53
10. REFERENCES 55
ORIGINAL PUBLICATIONS 75
6
LIST OF ORIGINAL PUBLICATIONS
I Heistaro S, Vartiainen E, Puska P. Trends in self-rated health in Finland 1972-1992.
Preventive Medicine 25:625-32, 1996.
II Heistaro S, Vartiainen E, Heliövaara M, Puska P. Trends of back pain in eastern
Finland, 1972-1992, in relation to socioeconomic status and behavioral risk factors.
American Journal of Epidemiology 148:671-82, 1998.
III Heistaro S, Laatikainen T, Vartiainen E, Puska P, Uutela A, Pokusajeva S, Uhanov
M. Self-reported health in the Republic of Karelia, Russia and in North Karelia, Finland
in 1992. European Journal of Public Health 11:74-80, 2001.
IV Heistaro S, Jousilahti P, Lahelma E, Vartiainen E, Puska P. Self-rated health and
mortality: a long-term prospective study in eastern Finland. Journal of Epidemiology &
Community Health 55:227-32, 2001.
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1. ABSTRACT
During the past decades, the health of the general population as measured by many
objective indicators – especially those related to premature mortality and many chronic
diseases – has improved in most industrialised countries, including Finland. The life
expectancy is nowadays longer than ever. This study was initiated to evaluate whether
people also feel healthier than earlier: there are more years in life, but is there more life
in those years?
The high rates of cardiovascular diseases, especially coronary heart disease, in Finland in
the beginning of the 1970s led to the launch of the North Karelia Project in 1972. The
Project carried out repeated population surveys (the FINRISK surveys) for its
evaluation, collecting data on cardiovascular diseases and their risk factors,
socioeconomic and psychosocial variables, medical history, health behaviour and
subjective health. Since 1972, comparable cross-sectional surveys have been carried out
in eastern Finland every fifth year, and since 1982 the surveys have been gradually
extended to other parts of Finland and in 1992 also to Russian Karelia.
We analysed trends and determinants of self-rated health and back pain over a 20-year
period in Finland and compared measures of subjective health between North Karelia,
Finland, and Pitkäranta, Russian Karelia. We also analysed the association between
self-rated health and mortality. Self-rated health is a central measure of subjective
health status.
Self-rated health improved markedly in eastern Finland during the period from 1972 to
1992. The development was more favourable for women than for men. High education
and high household income were associated with good subjective health status, but
among men the socioeconomic differences diminished during the study period.
There was a slightly decreasing trend in the prevalence of back pain among men, but
among women the prevalence rates remained stable. The prevalence rates differed
considerably between subgroups of the population. The trends varied markedly between
categories of some suspected risk factors for back pain, such as overweight and leisure-
time physical activity.
8
In North Karelia, Finland, people reported better self-rated health and less symptoms
than people in the neighbouring region of Pitkäranta, Republic of Karelia, Russia.
Socioeconomic differences in subjective health were less clear in the Republic of
Karelia.
Self-rated health was a strong predictor of mortality. Its predictive power was only
partly explained by medical history, cardiovascular disease risk factors, and education.
This association existed in both sexes for all-cause and cardiovascular mortality and,
especially among men, for mortality due to external causes. There was a clear gradient
from “good” through “average” to “poor” self-rated health in relation to all-cause and
cardiovascular mortality.
The goal for health promotion in the industrialised world has been to increase the
amount of healthy years, i.e. to postpone the age-related diseases into the later years of
life while simultaneously increasing life expectancy. Our results provide some
indications that when objective health status improves people also feel healthier.
9
2. INTRODUCTION
Health has several dimensions (Ware 1987, Litva and Eyles 1994, Smith et al. 1994),
and the contents of “good health” vary for different people (Tornstam 1975, Jylhä 1994,
Krause and Jay 1994, Wiseman 1999). During the past decades, the health of the general
population, as measured by many objective indicators, has improved in most
industrialised countries, especially with respect to premature mortality and many chronic
diseases. This improvement has occurred also in Finland. Nowadays life expectancy is
longer than ever has been the case in most countries. However, there is one important
question: do people also subjectively feel healthier than earlier? There are more years in
life, but is there more life in those years?
Self-reports are an economical and illustrative way of assessing people’s health (LaRue
et al. 1979, Fylkesnes and Førde 1991, McCallum et al. 1994, Fayers and Sprangers
2002). They reflect the more “objective” measures of health, like data from health
registers or physicians’ assessments, but can supplement this data with the subjective
perspective of health. Self-reports provide an indication of how people assess their own
health, but they are also correlated with medical and biological measures of health.
Furthermore, only individuals themselves are able to report pain and other symptoms
and, more generally, their subjective health status. With these considerations in mind
and due to the apparent simplicity of collecting data by self-reports on health, standard
questions on self-reported health are used in practically all health surveys.
In this work, the term “self-reported health” includes both reports on medical history,
e.g. previous diseases, and reports on subjective health status, including general or
global health and different symptoms. “Subjective” or “perceived” health reflects
personal assessments of an individual’s health status. “Self-rated health” is a specific
term for “general” or “global” health assessed by respondents themselves.
In Finland, active interventions to improve public health have been implemented since
the beginning of the 1970s. The rates of cardiovascular diseases and most cancers
among working-age population are known to have decreased. This has been well
documented and evaluated (Puska et al. 1993(a), Vartiainen et al. 1994(a), Vartiainen et
10
al. 1995, Puska et al. 1998, Vartiainen et al. 2000). Much less is known about trends in
subjective health, i.e. general health and symptoms, in the Finnish population as a
whole as well as in its subgroups. One of the most common symptoms in the general
population is back pain. Musculoskeletal pains, such as back pain, are important
contributors to subjective health status (Molarius and Janson 2002) and also a cause for
notable economic costs at the population level.
The high rates of cardiovascular diseases, especially coronary heart disease, in Finland in
the beginning of the 1970s (Keys 1970) led to the launch of the North Karelia Project in
1972. The aim of the Project was to lower the cardiovascular disease rates in North
Karelia by raising awareness in the population of the major medical risk factors, via the
implementation of a comprehensive, community-based intervention programme.
The North Karelia Project carried out repeated population surveys as an integral part of
its evaluation, collecting data on cardiovascular diseases and their risk factors,
socioeconomic and psychosocial variables, medical history, health behaviour and
subjective health. Since 1972, comparable cross-sectional surveys have been carried out
in eastern Finland every fifth year. Since 1982, these “FINRISK” surveys have been
gradually extended to other parts of Finland and in 1992 also to Russian Karelia.
In Russian Karelia, an area neighbouring eastern Finland, much less preventive health
activities have taken place. At the beginning of the 1990s, the risk factor and mortality
figures there resembled those found in Finland 20 years previously. Very little has been
known about the patterns of subjective health in Russian Karelia which, because of its
geographical and historical links, forms an interesting comparison with Finland,
especially with the region of North Karelia.
The general aim of this study was to assess measures of subjective health in Finland
where major public health activities have taken place to reduce premature mortality and
the incidence of major chronic diseases. We wanted to determine whether the great
improvement in public health in Finland was reflected also in people’s subjective health
status.
Therefore, we analysed trends and determinants of self-rated health, a central measure
11
of subjective health status, and back pain over 20 years in Finland. Furthermore, we
compared measures of subjective health in North Karelia, Finland, and Pitkäranta,
Russian Karelia. Finally, we analysed the association between self-rated health and
mortality.
12
13
3. LITERATURE REVIEW
3.1 Self-reports on health
Self-reports on medical history and previous illnesses seem to be reasonably valid if they
are compared with other sources, such as health examinations (Heliövaara et al. 1993).
Furthermore, self-reports are the only methods available if one wishes to assess
subjective aspects of health. The observed association between self-rated health and
mortality in many studies (Mossey and Shapiro 1982, Kaplan and Camacho 1983, Idler
et al. 1990, Wannamethee and Shaper 1991, Grant et al. 1995, Idler and Benyamini
1997, Jylhä et al. 1998, Martikainen et al. 2002) provides a sound foundation for
evaluations of subjective health. Of course, cultural background and factors such as
prevailing general welfare and health expectations have to be taken into account,
especially in international comparisons (Jylhä et al. 1998, Lynch et al. 2001, Sen 2002).
Doubts about the validity and significance of self-reports on health have been expressed
(Tissue 1972, McCallum et al. 1994, Sen 2002). Nonetheless, measures on self-reported
health status do correlate reasonably well with the individual’s health status as assessed
by a physician (Nagi 1969, Maddox and Douglass 1973, LaRue et al. 1979, Hunt et al.
1980, Kivinen et al. 1998). Statements of physicians or other professionals, which are
often regarded as the most objective measures of health, also have their problems with
objectivity and reliability (Markides et al. 1993).
Various indicators of physical capability are sometimes used as objective measures of
health. However, they are also limited in their capacity to reflect health as a whole. The
strength of subjective health status lies in that it reflects how a person actually feels
(Ware 1987, Blaxter 1989).
3.2 Socioeconomic factors and health
Socioeconomic status is associated with mortality, morbidity, and subjective health.
This association has been shown in different countries, e.g. Finland (Häkkinen 1991,
Pekkanen et al. 1995, Arinen et al. 1998), Scandinavian countries (Lundberg 1986,
Vågerö and Lundberg 1989, Rahkonen et al. 1993, Lahelma et al. 1994, Osler and
14
Klebak 1998, Dahl and Elstad 2001), Estonia (Leinsalu 2002), Britain (Blaxter 1987,
Vågerö and Lundberg 1989, Davey Smith et al. 1997, Hemingway et al. 1997, Power et
al. 1997, Hart et al. 1998), Ireland (O’Shea 1997), Germany (Helmert and Shea 1994,
Geyer and Peter 1999), the Netherlands (Gijsbers van Wijk et al. 1995), the United
States (Sorlie et al. 1995, Kaplan et al. 1996(a), Barnett et al. 1997), and Australia
(Taylor et al. 1992, Lawson and Black 1993, Turrell and Mathers 2000). Generally,
poor health is associated with lower socioeconomic status (Mackenbach et al. 1997).
Socioeconomic status can be measured and described by various indicators. Education is
a stable determinant of socioeconomic status (Klein-Hesselink and Spruit 1992,
Winkleby et al. 1992, Lahelma et al. 1994): it is individual and does not fluctuate with
time in the way that occupation or income can do. Education also avoids the problems in
assessments caused by unemployment. Household income is another widely used
variable when assessing the associations between socioeconomic factors and health.
Occupational status and income may be affected by illness, which makes them perhaps
less valid indicators than education.
In many countries education has been found to be an especially powerful factor
determining health outcomes (Valkonen 1989, Winkleby et al. 1992, Cavelaars et al.
1998) but not universally so in some countries, e.g. Russia (Palosuo et al. 1998, Carlson
2000). A high level of education is strongly associated with good subjective health
(Mossey and Shapiro 1982, Moum 1992). Socioeconomic status in general (Morrell
1972, Gyntelberg 1974, Walsh et al. 1992, Croft and Rigby 1994, Latza et al. 2000) and,
again, especially the degree of education (Nagi et al. 1973, Deyo and Tsui-Wu 1987,
Pincus et al. 1987, Dionne et al. 2001, Muller 2002), also seem to be inversely
associated with complaints of back pain, a major symptom causing ill-health.
The association between socioeconomic factors and health has remained fairly stable in
Finland during the past years (Manderbacka et al. 2001), though in men, educational
differences in health decreased in the period 1979-1993 (Lahelma et al. 1997(a)). There
is, furthermore, some evidence that health inequalities due to employment status
narrowed among men in Finland between 1986 and 1994 (Lahelma et al. 1997(b),
Lahelma et al. 2000). On the contrary, in Britain the inequalities seemed to have
widened or remained stable during the same period of time. In Norway (Dahl and Elstad
15
2001) and Sweden (Lundberg et al. 2001) the associations between low socioeconomic
position and health remained constant from the mid-1980s to the mid-1990s.
3.3 Self-rated health
Self-rated health is a widely used measure of the population’s health (Krause and Jay
1994). A single-item question such as “How would you describe your present health
status? Is it very good, quite good, average, quite poor, or very poor?” has been shown to
be a useful tool in population surveys. Subjective health status measured in this manner
is a strong predictor of future health problems (Weinberger et al. 1986, Weisen et al.
1999, Lee 2000, Idler et al. 2000), utilisation of health care services (Miilunpalo et al.
1997, Bath 1999), and mortality among the elderly (Mossey and Shapiro 1982, Idler et
al. 1990, Grant et al. 1995, Jylhä et al. 1998, Helmer et al. 1999) and even among
younger age groups (Kaplan and Camacho 1983, Wannamethee and Shaper 1991).
The association between self-rated health and mortality has been partly explained to be
caused by previous illnesses and socioeconomic factors, but in almost all of the studies
some part of the association has remained unexplained. Self-rated health is claimed to
predict mortality better among men than among women (Jylhä et al. 1998, Helmer et al.
1999, Idler et al. 2000).
Self-rated health has proved to be reliable in test-retest analysis (Lundberg and
Manderbacka 1996, Martikainen et al. 1999), and it forms a continuum from poor
through average to good in relation to most risk factors and ill-health indicators
(Manderbacka et al. 1998, Manor et al. 2000). Slightly different formulations on the
question on self-rated health are used, e.g. the number and definition of response
alternatives may vary, but the differences between parallel measures seem to be only
marginal (Eriksson et al. 2001, Fayers and Sprangers 2002).
Many studies conclude that self-rated health mainly reflects physical health status
(Ratner et al. 1998, Cott et al. 1999), especially the presence or absence of long-
standing diseases (Goldstein et al. 1984, Fylkesnes and Førde 1991, Kaplan et al.
1996(b), Manor et al. 2001). Indeed, self-rated health has a stronger association with
chronic conditions than acute illnesses (Goldstein et al. 1984, Fylkesnes and Førde
16
1991, Shadbolt 1997, Damian et al. 1999, Manor et al. 2001). A study from Tromsø,
Norway (Fylkesnes and Førde 1991) indicated that somatic symptoms, mainly those
connected with the musculoskeletal system, were most strongly associated with poor or
fair subjective general health. The authors suggested these symptoms would be
connected with the individual’s perception of his or her physical functional capabilities.
The structure of health status is, however, a complex construction including diseases,
disability, functional limitations (Jylhä et al. 2001), and health behaviour (Johansson and
Sundquist 1999, Manderbacka et al. 1999), and these factors also interact with each other
(Johnson and Wolinsky 1993, Leinonen et al. 2001(a)).
Overall, women report more symptoms than men (Tibblin et al. 1990, Rahkonen et al.
1993, Ross and Bird 1994, Gijsbers van Wijk et al. 1995, Sweeting 1995). Nonetheless,
Finnish women’s self-rated health has been found to be slightly better than that of
Finnish men (Lahelma et al. 1997(a)), and women live longer. The contents of “good
health” may be different for the sexes (Leinonen et al. 1999). In the Finnish Healthy
Village Study (Kumpusalo et al. 1992), subjective general health was associated with
physical capabilities among men, whereas among females it was more closely correlated
with other subjective health variables, in particular with pain symptoms. However, some
other studies (Krause and Jay 1994, Jylhä et al. 1998) have detected no significant
differences in the reference frames used by men and women.
Subjective health usually reveals a deterioration with advancing age (House et al. 1990,
Fylkesnes and Førde 1991, Lahelma et al. 1997(a)). This is understandable as most
diseases and functional limitations are more prevalent in older age groups (Rahkonen et
al. 1993), and these impairments cause feelings of ill-health, for example by limiting
physical activities of daily living (Leinonen et al. 1999, Jylhä et al. 2001). Adjusted for
medical conditions, age may show no relation to self-rated health (Kivinen et al. 1998).
Older people may also rank their present health by comparing it to their earlier health
status. On the other hand, subjective health is particularly informative when measuring
health among the young who do not suffer from severe illnesses (Vingilis et al. 2002). In
one study on this subject (Krause and Jay 1994) older people tended to rate their general
health by thinking about health problems, whereas subjects under 25 years of age more
frequently used health behaviours as a referent.
17
Some researchers have assessed self-rated health related to the respondents’ age peers
(Maddox and Douglass 1973, Weinberger et al. 1986, Eriksson et al. 2001). This
changes the composition quite substantially, because the concept of “good health” and
health expectations are not the same for different age groups (Leinonen et al. 1998).
Older, as well as chronically ill, people tend to adapt to the worsening of their health
(Manderbacka and Lundberg 1996, Leinonen et al. 2001(b)). In a recent German study
(Heindrich et al. 2002), self-ratings of health in comparison to those of the same age
were more consistently associated with mortality than global self-ratings of health.
There are some studies describing trends in self-rated health in Finland (Lahelma et al.
1997(a), Lahelma et al. 1997(b), Arinen et al. 1998, Aromaa and Koskinen 2002). They
suggest that the general health of Finnish adults has slightly improved in the past few
decades, especially among the middle-aged or older persons. The FINRISK data offers
unique possibilities for analysing these trends in the Finnish population and in its
subgroups since 1972. Furthermore, the present data with measured risk factors is most
suitable for analysing the association between self-rated health and mortality.
3.4 Back pain and other symptoms
There is a range of common symptoms present in the general population that have
received relatively little attention. These include somatic symptoms like swelling of
lower limbs, varicose veins, constipation, recurrent stomach complaints plus a variety
of psychosomatic symptoms. It is difficult to associate these symptoms with diagnoses
of specific diseases in epidemiological studies. Nevertheless, these symptoms have a
major role in the deterioration of people’s quality of life and they are a common cause
for individuals to seek assistance from health care professionals.
Musculoskeletal complaints constitute a major public health problem throughout the
industrialised world (Cunningham and Kelsey 1984, Sievers and Klaukka 1991, Walsh
et al. 1992, Croft and Rigby 1994) and are responsible for major financial costs to
society (Cypress 1983, Heliövaara et al. 1989, Slätis and Ruusinen 1991, Frank 1993,
Rekola et al. 1993, Carey et al. 1996). In particular, back pain is a common and
disabling condition among the general population in the western countries (Nagi et al.
18
1973, Gyntelberg 1974, Cunningham and Kelsey 1984, Sievers and Klaukka 1991,
Walsh et al. 1992, Croft and Rigby 1994, Leboeuf-Yde et al. 1997, Elliott et al. 1999,
Mounce 2002), and without doubt is a factor leading to poorer subjective global health
(Molarius and Janson 2002).
The social costs of back problems are high (Frank 1993) because of early retirement,
sick leaves, and a frequent use of health care services (Nagi et al. 1973, Gyntelberg
1974, Cypress 1983, Heliövaara et al. 1989, Rekola et al. 1993, Carey et al. 1996). There
are various etiological causes for back pain. In many cases clinical tests and
examinations may reveal no clearly identifiable cause, such as sciatica (Heliövaara et al.
1989), for these symptoms. Some interventions to address the back pain problem at a
population level have been tried (Buchbinder et al. 2001, Linton and van Tulder 2001),
but so far preventive methods are rare.
There are also a vast number of behavioural and environmental risk factors for back
pain. Workload, particularly heavy lifting (Frymoyer et al. 1983, Penttinen 1987, Lau et
al. 1995), is known to be associated with back trouble (Gyntelberg 1974, Heliövaara et
al. 1991, Behrens et al. 1994, Heliövaara 1999, Hoogendoorn et al. 1999, Bildt
Thorbjörnsson et al. 2000, Hartvigsen et al. 2001). Leisure-time physical inactivity
(Gyntelberg 1974, Frymoyer et al. 1983, Hoogendoorn et al. 1999), high body mass
index (Gyntelberg 1974, Biering-Sörensen 1984, Penttinen 1987, Deyo and Tsui-Wu
1987, Walsh et al. 1992, Leboeuf-Yde et al. 1999, Leboeuf-Yde 2000), and smoking
(Frymoyer et al. 1983, Battie et al. 1989, Battie et al. 1991, Heliövaara et al. 1991, Pietri
et al. 1992, Boshuizen et al. 1993, Ernst 1993, O’Connor and Marlowe 1993, Croft and
Rigby 1994, Bildt Thorbjörnsson et al. 2000) are potential risk factors of back pain,
though the evidence is somewhat controversial.
Some Finnish studies assessing the trends of back pain have been published (Leino et
al. 1994, Manninen et al. 1996). They suggest that the prevalence of back pain in the
population has remained constant or shown a slight downward trend. Our data from five
comparable, cross-sectional surveys, however, provide a new perspective on the trends
and background factors of back pain over the 20-year period.
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3.5 The health of the inhabitants of Russian Karelia, a region which
borders Finland
The states of the former Soviet Union have been undergoing rapid economic, social and
political change during the past years. It is obvious that the great challenges which
accompany the change that Russia is experiencing are being reflected in people’s health
(Bobak et al. 1998, Kawachi et al. 1999).
During most of the Soviet period a fairly closed border separated Finland from the
Soviet Union and their two very different systems of society. Major differences are now
known to exist between eastern Finland and the neighbouring Republic of Karelia,
Russia, e.g. in mortality and cardiovascular disease risk factors as well as lifestyles
(Puska et al. 1993(b), Matilainen et al. 1994, Puska 1995, Matilainen et al. 1996). In
many respects, especially concerning the high rates of chronic diseases, the rather
unfavourable health situation in the Republic of Karelia, Russia, resembles that found in
eastern Finland a few decades ago (Puska 1995(a)) before active interventions to
improve public health were initiated in North Karelia. Thus Russian Karelia forms an
interesting comparison to Finland, especially to North Karelia in Finland.
Little is known about the differences in subjective measures of health between these
two closely neighbouring areas. Do they reflect the differences in mortality or in
chronic disease rates? The survey which was carried out in both areas in 1992 offers a
good opportunity to compare subjective health variables across the former East-West
border.
20
21
4. AIMS OF THE STUDY
The aim of this study was to find out whether the great improvement in public health in
the national targets has been reflected in the subjective health of people – another
important goal in our health work.
Generally, the aim was to learn more about subjective health of individuals in Finland
where major public health activities have taken place to reduce premature mortality and
the incidence of major chronic diseases. The large data collected in the FINRISK
surveys provides unique possibilities for such an evaluation. More specifically, the aims
of the study were to address the following questions:
� has the self-rated health of the population improved during the period 1972-1992,
and how has this development impacted on different population groups?
� how has the development been with respect to back pain – a major contributor to
prevalent ill-health – taking into account socioeconomic status and behavioural risk
factors of back pain?
� is there a difference in subjective health between Finnish and Russian Karelia that
would be in agreement with the mortality difference, and are the differences in self-
rated health in Russian Karelia similar to those in Finland?
� how does self-rated health predict mortality and to what extent can this be explained
by medical history, cardiovascular disease risk factors, and education?
22
23
5. MATERIALS AND METHODS
5.1 The FINRISK surveys
Comparable cross-sectional studies have been carried out every fifth year since 1972 in
the eastern provinces of North Karelia and Kuopio, the latter being a reference area
during the initial 5-year period of the North Karelia Project. During the following years,
these surveys were extended to other areas of Finland in order to facilitate risk factor
monitoring at a national level (the “FINRISK” surveys). A third area in southwestern
Finland, including the city of Turku, the town of Loimaa, and 12 minor rural
municipalities, was included in 1982.
The fifth survey in 1992 was also conducted in the district of Pitkäranta, Russia, based
on an agreement between the Ministry of Health of the Republic of Karelia, Russia, and
the Finnish National Public Health Institute. The Republic of Karelia is an autonomous
part of the Russian Federation with 802,000 inhabitants (1991) and the district of
Pitkäranta (28,000 inhabitants) is one of the Republic’s 17 districts. Pitkäranta was
chosen as the study area because its population was well-representative of the whole
population of the Republic of Karelia (Kellera 1990). Of the population of the
Pitkäranta district, 50% live in the town of Pitkäranta on the shores of Lake Ladoga.
5.2 Samples
For each of the five surveys, independent random samples were drawn from the
population register. In 1972 and 1977, a random sample of 6.6% (except in article IV,
13.2% in the city of Joensuu in North Karelia) of the population born during 1913-47
was drawn in the North Karelia and Kuopio provinces. In 1977, an additional 6.6%
random sample of the population born between 1948 and 1952 was drawn in North
Karelia (included only in the article IV study).
In 1982, 1987 and 1992 the target population consisted of people between the ages of 25
and 64 years in the three areas, and in these three surveys at least 250 persons of each
sex and ten-year age group were randomly chosen for the sample in each of the three
areas. In the Pitkäranta sample in 1992, each sex-specific, ten-year age group had 125
24
persons.
For article IV, mortality data until 1995 were collected from the national mortality
register using personal identification numbers.
The age range considered in the longitudinal analyses in articles I and II was 30 to 59
years, this being the common range in all five surveys. Sample sizes and participation
rates in North Karelia and Kuopio provinces are given in Table 1. The response rates
were over 90% in the 1972 survey but somewhat lower in the later surveys. In women,
the response rates were higher than in men. The response rates in southwestern Finland
varied between 75-82% among men and between 83-87% among women during 1982-
1992. In Pitkäranta in 1992, the response rate was 77% among men and 92% among
women.
Table 1. Samples (n) and participation rates (%) by year, sex and area, age range 30 to 59 years.
MEN WOMEN
North Karelia Kuopio Province North Karelia Kuopio Province Year n % n % n % n %
1972 1959 94 2918 91 2056 96 2949 941977 2063 87 2933 89 2020 91 2996 921982 1599 77 1459 83 1511 84 1143 881987 1521 79 762 82 1485 87 744 871992 759 69 768 76 750 82 735 85
5.3 Methods of collecting data
The surveys were carried out by mailing a self-administered questionnaire to the
subjects. A member of a trained research team took standardised risk factor
measurements, e.g. blood pressure, height, weight, and blood samples. In 1992, the
main risk factor measurements were carried out by the same Finnish study nurses both
in North Karelia and in Pitkäranta. The research team also checked whether the
questionnaires were properly completed and, if necessary, helped the subjects to
complete them. The subjects usually filled in the questionnaire at home but in
Pitkäranta this was done at the local health centre prior to the examination.
25
Education was measured as the total number of school years. Because the mean length
and the structure of the Finnish education system had changed markedly during the 20th
century, we divided the respondents into educational tertiles according to their birth
years, by sex. For example, all those born in 1930, independent of which survey(s) they
had taken part in, were divided into three educational groups of equal size, according to
the number of their school years. The questionnaire defined “school years” as all
education beginning with elementary school. In article III, the respondents were divided
into educational tertiles in their respective 10-year age groups in both areas, North
Karelia and Pitkäranta, the two areas and sexes separately.
The respondents were also sorted into separate groups by their household income. They
were asked to choose one of provided alternative income groups, determined by gross
household income per year. The participants of each of the five surveys were then
assigned to one of the two income groups of roughly equal sizes. In the Pitkäranta study
(article III), the respondents were sorted into three income groups by area.
The subjects were asked to rate their present general health status along a five-point
scale: “very good” to “quite good” to “average” to “quite poor” to “very poor”. Self-
rated health measured in this manner has proved to be reliable in test-retest analysis
(Lundberg and Manderbacka 1996, Martikainen et al. 1999). The participants’ self-
reported physical condition was assessed using a similar five-point scale.
Furthermore, the participants were asked whether they had had the following somatic
symptoms during the preceding month (30 days): rheumatic complaints, joint pain, back
pain or backache, swelling in lower limbs, varicose veins, constipation, recurrent
stomach complaints, malaise, powerless lower limbs, dry mouth or a stuffy nose. The
response alternatives were “yes” and “no”.
The respondents were also asked how often 13 given psychosomatic symptoms had
occurred or had bothered them during the preceding month (30 days). The symptoms
listed were accelerated heart beat, becoming confused when doing a task quickly,
trembling hands, excitedness and nervousness, frightening thoughts, tiredness and
overstrain, irregular heartbeats, dizziness (vertigo), nightmares, depression,
26
sleeplessness (insomnia), headache and sweating of hands. There were three response
alternatives: “often”, “sometimes” and “not at all”. All the questions concerning
somatic or psychosomatic symptoms remained identical over the five surveys.
Data on the subjects’ medical history were collected by asking if a physician had
diagnosed or treated the following diseases during the past 12 months: myocardial
infarction, stroke, elevated blood pressure, heart failure, angina pectoris, bronchial
asthma, emphysema/bronchitis, and rheumatoid arthritis. The questionnaire also had
questions about the respondents’ smoking status, occupation, workload, and leisure
time physical activity.
5.4 Statistical methods and data analysis
Prevalence rates are presented for self-rated health, back pain and other symptoms in the
descriptive analyses. The analysis of variance was used to assess the continuous
variables. Logistic regression models were the main statistical methods used to analyse
the trends and differences in the population and its subsamples, and proportional hazards
(Cox) regression was used in the survival analyses in article IV. All statistical analyses
were done using SAS programs (SAS Institute Inc. 1989).
5.5 Further analyses in the results section
In order to assess the trends and determinants of self-rated health more thoroughly, we
present some new analyses on self-rated health using the same FINRISK material 1972-
1992. We again pooled together the data collected in North Karelia and Kuopio
provinces 1972-1992 and excluded the subjects with missing data on self-rated health,
survey year, survey area, age, education, smoking, measured systolic blood pressure,
serum cholesterol, body mass index, and leisure time physical activity. Furthermore,
concerning the diseases diagnosed or treated by a doctor, somatic and psychosomatic
symptoms, we replaced the missing values by the alternative “no disease/symptom”.
This meant that we had a total of 13,076 men and 13,600 women for whom we had
complete data.
We used logistic regression models to analyse how potential changes in the background
27
variables might have influenced the observed improvement in self-rated health between
1972 and 1992, and to assess the stability and strength of these background factors as
determinants of less-than-good self-rated health. Age, systolic blood pressure, serum
cholesterol, and body mass index were used as continuous variables, showing adequate
linearity in relation to self-rated health.
28
29
6. RESULTS
The results are presented in detail in articles I to IV.
6.1 Trends in self-rated health (Article I)
The aim of article I was to evaluate trends in self-rated health in different subgroups of
the population during 1972-1992. Self-reported general health improved clearly among
both sexes during the follow-up (Figure 1). In 1972, 34% of men reported good health
status, and the corresponding rate in 1992 was 50%. Among women, the development
was even more favourable. The levels of self-rated health among both sexes were equal
in 1972 and 1977, but by 1982 already 51% of women reported good health status
compared to 45% of men. In 1992, there was a ten per cent gap between men and
women, 50 and 60%, respectively.
Figure 1. The percentages of those who reported “good” health status, North Karelia and Kuopio Province,
age range 30 to 59 years.
Men in southwestern Finland reported somewhat better health status than men in eastern
Finland during 1982-1992. In southwestern Finland, also women reported slightly higher
rates of good health in 1982 and 1987 than in the eastern survey areas. Subjective
30
35
40
45
50
55
60
65
70
1972 1977 1982 1987 1992
%
MENWOMEN
30
general health improved in all age groups among both sexes. The improvement was
somewhat more marked among those aged 40 to 49 years.
Education had a strong association with subjective health among both sexes. In men this
was most evident in the 1970s, and if one assesses the whole period from 1972 to 1992
the educational differences diminished statistically significantly. The difference between
the groups with low and middle education observed in the 1970s disappeared during the
1980s. In women, the two lower educational groups differed from each other only
slightly between 1972 and 1982, with a clear but somewhat narrowing gap favouring the
group with the highest education. There were also considerable differences in subjective
health according to household income, though in men the gap reduced statistically
significantly between 1972 and 1992.
In summary, self-rated health improved considerably among both sexes, more among
women than men. Low socioeconomic status was associated with less-than-good self-
rated health, but in men its importance as a predictor of less-than-good health
diminished.
6.2 Trends of back pain (Article II)
The aim of this article was to analyse the trends in back pain during 1972-1992 in
different population subgroups determined by sociodemographic factors and potential
behavioural risk factors of back pain. Nearly half of the study population reported that
they had experienced back pain during the preceding month (Figure 2).
Over the 20-year period, the overall prevalence of back pain exhibited a downward trend
when both sexes were assessed together. Controlled for age alone, the declining trend
was statistically significant among men but not among women. However, the sex
differences in the 20-year prevalence or in the 20-year trend were not statistically
significant. The age group differences remained stable during 1972-1992.
31
Figure 2. Age-adjusted prevalence rates of back pain during the preceding month among men and women,
North Karelia and Kuopio Province, age range 30 to 59 years.
Those with the highest education had statistically significantly less back pain than the
groups with middle or low education, and this difference remained stable over the 20
years among both sexes. Low household income was inversely associated with back
pain. This disparity between the two income categories, however, diminished during
1972-1992.
Occupation and workload showed obvious and time-stable associations with back pain,
i.e. those who did physically more demanding work experienced more back pain.
Leisure-time physical activity was associated with less back pain among both sexes, but
this association was more stable among men than among women. Body mass index was
directly proportional to the prevalence of back pain among women but not among men,
even when the other risk determinants were controlled. However, in 1987 and 1992, the
body mass index category differences also seemed to become obvious among men.
40
42
44
46
48
50
52
54
56
58
60
1972 1977 1982 1987 1992
%
MENWOMEN
32
Male smokers and ex-smokers of both sexes reported statistically significantly more
back pain than never-smokers. In men this association was consistent over the 20 years.
In women, the trends were statistically significantly different for never-smokers and ex-
smokers.
6.3 North Karelia and Pitkäranta (Article III)
The aim of article III was to assess different measures of subjective health in North
Karelia, Finland, and in the neighbouring district of Pitkäranta, Russia. In North Karelia
50% of men reported quite good or very good health, while the corresponding rate was
34% in Pitkäranta. Among women, the percentages were 58% in North Karelia and
22% in Pitkäranta. The differences between the areas were statistically significant in all
sex-age groups, except among men over 45 years of age.
Household income was related to good self-rated health among women in North Karelia
and in Pitkäranta. Among men, the relationship was not as clear. The association
between self-rated health and household income was similar in the two areas among
both sexes. Education was positively associated with good self-rated health among both
sexes in North Karelia, as well as among women but not men in Pitkäranta.
North Karelians, particularly women, reported their physical condition as good more
often than subjects in neighbouring Pitkäranta. Psychosomatic symptoms were
statistically significantly more prevalent in Pitkäranta among both sexes.
Many somatic symptoms were statistically significantly more prevalent in Pitkäranta
including rheumatic complaints, back pain, constipation and recurrent stomach
complaints among women and joint pain, malaise, powerless lower limbs and dry
mouth among both sexes. North Karelian men reported swollen limbs, constipation and
stuffy noses statistically significantly more frequently, while North Karelian women
reported varicose veins and stuffy noses more often than Pitkäranta women.
To summarise, most subjective health indicators favoured North Karelia, Finland. The
socioeconomic differences in self-rated health were less pronounced in Pitkäranta,
Russia.
33
6.4 Self-rated health and mortality (Article IV)
The aim of article IV was to analyse the association between self-rated health and
mortality in a large cohort of individuals in eastern Finland. For self-rated health, the
age-adjusted “poor” to “good” relative risk for all-cause mortality during 1972/1975-
1995 was 2.36 (2.10-2.64) for men and 1.90 (1.63-2.22) for women, and for
cardiovascular mortality 2.29 (1.96-2.68) for men and 2.34 (1.84-2.96) for women.
Adjusted for the selected potentially fatal diseases from the medical history,
cardiovascular disease risk factors, and education, the corresponding relative risks for
all-cause mortality were 1.66 (1.47-1.88) for men and 1.50 (1.26-1.78) for women, and
for cardiovascular mortality 1.54 (1.29-1.82) for men and 1.63 (1.26-2.10) for women
(Figure 3).
A gradient from “good” through “average” to “poor” self-rated health in relation to all-
cause and cardiovascular mortality was found. Among women, the relative risks for the
“average” group were only marginally statistically significant after the adjustments.
The association between self-rated health and mortality due to external causes was
fairly strong among men. For women, the relative risk for “average” self-rated health
was greater than that for “poor” health (Figure 3).
Assessing a shorter period, 1972/1977-1985, among men the association between self-
rated health and mortality was slightly stronger than during the longer follow-up
1972/1977-1995. The relatively small number of deaths among women may explain
that the association was not so strong as during the longer follow-up. Combining men
and women, the association between self-rated health and all-cause and cardiovascular
mortality was statistically significant, and there was a gradient from “good” through
“average” to “poor” health.
34
MEN
WOMEN
Figure 3. Self-rated health in relation to mortality between 1972/1977-1995: relative risks for fully
adjusted models, “good” health = 1.00. ALL = all-cause mortality, CVD = cardiovascular diseases
mortality, EXT = external causes mortality.
11.11.21.31.41.51.61.71.81.9
2
ALL CVD EXT
AVERAGEPOOR
11.11.21.31.41.51.61.71.81.9
2
ALL CVD EXT
AVERAGEPOOR
35
6.5 Further analyses
These additional analyses aimed to assess the trends and determinants of self-rated
health in more depth. Table 2 shows how the odds ratio for a 5-year change in self-rated
health changed when certain blocks of background variables were fitted into the model.
The basic model was adjusted only for survey area, age, and education. Block 1 consists
of conditions diagnosed or treated by a doctor, block 2 of somatic symptoms, block 3 of
psychosomatic symptoms, and block 4 of (cardiovascular disease) risk factors. The
contents of the blocks are presented in detail in Table 3.
Table 2. Trends for self-rated health 1972-1992, logistic regression models by sex. North Karelia andKuopio provinces, 1972, 1977, 1982, 1987, and 1992 samples pooled together, age range 30 to 59years. All the models were adjusted for survey area, age (continuous variable), and education. The oddsratios represent the average change for a 5-year period between two succesive surveys.
MEN (n=13,076)
Models Odds Ratio for Survey Year (95% CI)
Basic 0.806 (0.782-0.830)+ Block 1 0.804 (0.779-0.829)+ Block 2 0.815 (0.789-0.843)+ Block 3 0.865 (0.835-0.896)+ Block 4 (full model) 0.887 (0.854-0.921)
WOMEN (n=13,600)
Models Odds Ratio for Survey Year (95% CI)
Basic 0.722 (0.701-0.743)+ Block 1 0.731 (0.710-0.754)+ Block 2 0.721 (0.697-0.745)+ Block 3 0.743 (0.718-0.770)+ Block 4 (full model) 0.788 (0.759-0.819)
As shown in Table 2, the changes in the background variables (blocks 1 to 4) included
explained only a part of the improvement in self-rated health during 1972-1992.
Table 3 shows the full model with all the variables (blocks 1 to 4) included
simultaneously in the same model, separately for men and women. Most selected items
36
of diagnosed diseases and somatic or psychosomatic symptoms were independently
associated with less-than-good self-rated health. However, this was not the case
concerning so called silent risk factors, serum cholesterol (among men) and systolic
blood pressure (among both sexes).
The relationship between symptoms and conditions was mainly as expected, i.e. they
were associated with less-than-good health. The exceptions were that nightmares
among men and frightening thoughts among women seemed to be associated with
better self-rated health. Education and leisure time physical activity were strongly
associated with good health among both sexes. Higher body mass index was associated
with poorer health among both sexes, but smoking only among men.
In these adjusted models, the area difference between North Karelia and Kuopio
provinces was statistically non-significant among both sexes.
The odds ratio for back pain, adjusted with only survey, survey area, age, and
education, was 2.714 (2.510-2.934) among men and 2.753 (2.550-2.973) among women
(not shown in the tables). Thus back pain was a strong contributor to subjective ill-
health.
Table 4 shows the statistical significances for the interactions between survey year and
each variable to reveal the stability of the association between self-rated health and that
particular variable. The interactions of each block from 1 to 4 were modeled separately
because of the large size of the models. The stability was evident for most of the
variables selected, which means that they were associated with self-rated health in a
stable manner over the 20 years.
37
Table 3. Odds ratios from the same logistic regression model for potential determinants of less-than-good self-rated health, by sex. North Karelia and Kuopio provinces, 1972, 1977, 1982, 1987, and 1992samples pooled together, age range 30 to 59 years.
MEN (n=13,076)
Variable Odds Ratio (95% CI) p Value
Survey (1. to 5.) 0.887 0.854, 0.921 0.000Area (Kuopio vs. North Karelia) 0.960 0.880, 1.048 nsAge (a 1.068 1.062, 1.074 0.000Education (classes 1,2,3) 0.808 0.764, 0.856 0.000
Block 1 (yes/no)Elevated blood pressure 1.711 1.467, 1.996 0.000Heart failure 2.954 1.926, 4.532 0.000Angina pectoris 1.947 1.452, 2.609 0.000Asthma bronchiale 3.794 2.205, 6.526 0.000Emphysema/Bronchitis 1.631 1.281, 2.077 0.000Rheumatoid arthritis 2.528 1.520, 4.204 0.000
Block 2 (yes/no)Rheumatic complaints 1.334 1.157, 1.538 0.000Joint pain 1.520 1.353, 1.707 0.000Back pain 1.723 1.576, 1.885 0.000Swollen lower limbs 1.742 1.319, 2.300 0.000Varicose veins 1.028 0.858, 1.232 nsConstipation 1.250 1.038, 1.506 0.019Recurrent stomach complaints 1.798 1.580, 2.046 0.000
Block 3 (no, sometimes, often)Accelerated heart beat 1.250 1.139, 1.371 0.000Confusion in thought processes 1.185 1.074, 1.308 0.001Trembling hands 1.388 1.265, 1.524 0.000Excitedness, nervousness 0.967 0.879, 1.064 nsFrightening thoughts 1.066 0.952, 1.194 nsExhaustion, overstrain 1.497 1.376, 1.629 0.000Irregular heartbeats 1.378 1.239, 1.533 0.000Vertigo (Dizziness) 1.424 1.289, 1.575 0.000Nightmares 0.889 0.810, 0.976 0.014Depression 1.195 1.079, 1.325 0.001Insomnia 1.230 1.124, 1.345 0.000Headache 1.162 1.078, 1.252 0.000Sweating hands 1.020 0.930, 1.119 ns
Block 4Smoker/non-smoker 1.367 1.250, 1.494 0.000Systolic blood pressure (b 1.001 0.999, 1.004 nsSerum cholesterol (c 1.016 0.979, 1.054 nsBody mass index (d 1.040 1.026, 1.054 0.000Leisure time physical activity (e 0.654 0.612, 0.699 0.000
(a per one year(b per one mmHg(c per one mmol/L(d per one kg/m2(e low, moderate, high
38
WOMEN (n=13,600)
Variable Odds Ratio (95% CI) p Value
Survey (1. to 5.) 0.788 0.759, 0.819 0.000Area (Kuopio vs. North Karelia) 0.991 0.909, 1.079 nsAge (a 1.062 1.056, 1.069 0.000Education (classes 1,2,3) 0.771 0.730, 0.814 0.000
Block 1 (yes/no)Elevated blood pressure 1.384 1.204, 1.592 0.000Heart failure 3.423 2.198, 5.332 0.000Angina pectoris 1.596 1.143, 2.230 0.006Asthma bronchiale 2.444 1.632, 3.659 0.000Emphysema/Bronchitis 1.743 1.371, 2.217 0.000Rheumatoid arthritis 3.391 2.367, 4.858 0.000
Block 2 (yes/no)Rheumatic complaints 1.265 1.106, 1.447 0.001Joint pain 1.679 1.512, 1.865 0.000Back pain 1.580 1.446, 1.726 0.000Swollen lower limbs 1.196 1.073, 1.334 0.001Varicose veins 0.973 0.883, 1.073 nsConstipation 1.084 0.953, 1.232 nsRecurrent stomach complaints 1.876 1.657, 2.125 0.000
Block 3 (no, sometimes, often)Accelerated heart beat 1.082 0.987, 1.187 nsConfusion in thought processes 1.173 1.074, 1.281 0.000Trembling hands 1.355 1.233, 1.490 0.000Excitedness, nervousness 0.985 0.896, 1.084 nsFrightening thoughts 0.890 0.810, 0.979 0.017Exhaustion, overstrain 1.638 1.510, 1.777 0.000Irregular heartbeats 1.267 1.154, 1.391 0.000Vertigo (Dizziness) 1.405 1.291, 1.528 0.000Nightmares 0.960 0.882, 1.044 nsDepression 1.132 1.033, 1.241 0.008Insomnia 1.305 1.202, 1.416 0.000Headache 1.309 1.218, 1.405 0.000Sweating hands 0.967 0.876, 1.068 ns
Block 4Smoker/non-smoker 1.124 0.992, 1.274 nsSystolic blood pressure (b 1.002 1.000, 1.005 nsSerum cholesterol (c 1.059 1.020, 1.099 0.003Body mass index (d 1.040 1.029, 1.052 0.000Leisure time physical activity (e 0.660 0.618, 0.704 0.000
(a per one year(b per one mmHg(c per one mmol/L(d per one kg/m2(e low, moderate, high
39
Table 4. Statistical significances (p values) for the interaction terms “survey year X variable” forpotential determinants of less-than-good self-rated health, logistic regression models by sex. NorthKarelia and Kuopio provinces, 1972, 1977, 1982, 1987, and 1992 samples pooled together, age range30 to 59 years. All the models were adjusted for age (continuous variable), survey area, and education.
MEN WOMENVariable (n=13,076) (n=13,600)
Model 1 (yes/no)Elevated blood pressure ns 0.003Heart failure ns nsAngina pectoris 0.020 0.004Asthma bronchiale ns nsEmphysema/Bronchitis ns nsRheumatoid arthritis ns 0.016
Model 2 (yes/no)Rheumatic complaints ns nsJoint pain ns 0.013Back pain ns nsSwollen lower limbs ns nsVaricose veins ns nsConstipation ns nsRecurrent stomach complaints 0.018 ns
Model 3 (no, sometimes, often)Accelerated heart beat ns nsConfusion in thought processes ns nsTrembling hands ns 0.005Excitedness, nervousness ns nsFrightening thoughts ns nsTiredness, overstrain ns nsIrregular heartbeats ns 0.017Vertigo (Dizziness) ns nsNightmares ns nsDepression ns nsInsomnia ns nsHeadache ns nsSweating hands ns ns
Model 4Smoker/non-smoker ns nsSystolic blood pressure (b ns nsSerum cholesterol (c 0.030 nsBody mass index (d 0.011 nsLeisure time physical activity (e ns ns
(a per one year(b per one mmHg(c per one mmol/L(d per one kg/m2(e low, moderate, high
40
41
7. DISCUSSION
We analysed trends and determinants of subjective health status in Finland and
measures of subjective health in Russian Karelia using the data collected in the national
FINRISK surveys during 1972-1992. The five cross-sectional population surveys with
comparable data offered unique possibilities to assess time trends in subjective health
variables, self-rated health and back pain. By linking the data of the two earliest surveys
to data from mortality registers, we were able to analyse the association between self-
rated health and mortality in a large randomly selected population cohort. The cross-
sectional analyses comparing North Karelia, Finland, and Pitkäranta area, Russia,
revealed subjective health differences across the former border between East and West.
Our results provide some indications that when objective health status improves people
also actually feel healthier.
Self-rated health improved markedly in eastern Finland between 1972 and 1992. The
development was more favourable for women than for men. Among men the
development was more positive in North Karelia than in Kuopio province between 1972
and 1982, which may reflect the impact of the North Karelia Project.
High education and high household income were associated with good subjective health
status, but among men the socioeconomic differences diminished during the study
period, which is accordant with other Finnish studies (Lahelma et al. 1997(a), Lahelma
et al. 1997(b)).
Nearly half of the study population reported back pain during the preceding month.
There was a decreasing trend in the prevalence of back pain among men over the survey
years. The prevalence rates differed considerably between subgroups of the population.
The trends varied markedly between categories of some suspected risk factors for back
pain, such as overweight and leisure-time physical activity – in other words, their
association with back pain was not stable. The differences in back pain prevalence
according to household income diminished during 1972-1992.
In North Karelia, Finland, people reported better self-rated health and less symptoms
than people in the neighbouring region of Pitkäranta, Republic of Karelia, Russia.
42
Socioeconomic differences in subjective health were less clear in the Republic of
Karelia.
Self-rated health was a strong predictor of mortality, and its predictive power was only
partly explained by medical history, cardiovascular disease risk factors, and education.
The association existed for both sexes for all-cause and cardiovascular mortality and,
especially among men, for mortality due to external causes. There was a clear gradient
from “good” through “average” to “poor” self-rated health in relation to all-cause and
cardiovascular mortality.
7.1 Comments on the materials and methods used in this work
The medical history and most other variables used in this work were self-reported.
Doubts have been raised about the validity and significance of self-reports on health
(Tissue 1972, McCallum et al. 1994). Self-reports on medical history, however, have
proved to be quite reliable even when compared with more objective information
sources, especially when the health conditions are severe and clearly defined
(Heliövaara et al. 1993, Zhu et al. 1999). The validity of self-reports has been shown
also with respect to the use of health services (Reijneveld and Stronks 2001). Self-
reports are useful and economical when assessing people’s health (Martini and
McDowell 1976, LaRue et al. 1979, Fylkesnes and Førde 1991) particularly in large
population studies.
Questionnaires and interviews are in fact the only available methods of gathering
information on subjective health and symptoms. Subjective health status seems to
correlate rather well with the health status determined by a physician (Friedsam and
Martin 1963, Maddox and Douglass 1973, Martini and McDowell 1976, LaRue et al.
1979). Assessments of physicians and other professionals, which are often regarded as
the most objective measures of health, also have their problems of validity (Markides et
al. 1993).
It is clear that our questions on self-rated health and symptoms are rather crude methods
in assessing people’s health, and many cultural factors as well as general welfare have to
be taken into account especially in international comparisons (Sen 2002). On the other
43
hand, these kinds of questions are simple enough to be understood similarly among
respondents and they are thus valuable tools in population studies. The formulation of
the questions remained the same over the study period. It is difficult to assess whether
the meaning of the questions was understood in the same way over the 20-year period.
In this work the only way to measure back pain was also through self-reports given on
the questionnaires. “Low back pain” is the term used to describe back pain complaints in
most studies. In the Finnish language, however, the terms “back pain” or “back ache” are
common language and are understood as referring to pain in the lumbar or thoracic back
but not in the neck or shoulder region.
The way different persons develop and express pain symptoms varies to a great extent,
for example, psychological factors (Block et al. 1996, Linton 2000) and cultural
background (Honeyman and Jakobs 1996) have a role. The manner in which people
express pain may even change with time, accompanied with changes in general health
expectations as well as changes in the health care and social insurance systems.
Finland is a country with a relatively homogenous population. All known health
indicators are changing in the same direction in different areas of Finland. Thus it is very
likely that most our results from these studied areas of Finland can be extrapolated to the
rest of the country.
Well-to-do population groups are perhaps more likely to participate in these kinds of
surveys, leading to an upward bias in the results, especially in cross-sectional
comparisons. In this respect it should be noted that in 1992, North Karelian response
rates were somewhat lower than the corresponding rates in Pitkäranta. Although the
response rates in Finland in the two surveys in the 1970s were somewhat higher than in
the later ones, it is not likely that there is any major bias for this reason in the trend
results. However, it is not possible to provide an estimate of the magnitude of the effect
that this phenomenon may have had on the results.
Concerning the Pitkäranta survey in 1992, it should be noted that the language used in
Pitkäranta was Russian. Although the questionnaires were carefully checked for
accuracy of the translation, some items and concepts, like “physical condition”,
44
“malaise”, or “average”, may have different meanings in the two cultures (Palosuo
2000), and this must be taken into account when interpreting the results.
7.2 General developments of health in Finland
It has been shown that ischaemic heart disease and stroke mortality has decreased by
about 50 per cent among working-age people in Finland between 1972 and 1992, with
most of this decline being attributable to changes in known risk factors such as smoking,
blood pressure, and cholesterol levels (Vartiainen et al. 1994(b), Vartiainen et al. 1995,
Vartiainen et al. 2000). Also total and lung cancer mortality have declined (Puska et al.
1993(a)). The improvement in subjective general health found in our study can be
explained at least partly by these reduced disease rates.
Generally, there was a rapid improvement in the patterns of health behaviour related to
major chronic diseases in the 1970s, followed by a more steady development (Helakorpi
et al. 2001). Food habits have changed for the better among Finns during the past
decades. However, the consumption of alcohol has increased quite steadily, and the
share of non-drinkers has decreased. Leisure-time physical activity has increased in
Finland since the early 1980s. Overweight has increased in both sexes since the late
1970s to the present day.
Women may have taken more advantage of health information than men. The
cardiovascular risk factors, blood pressure and cholesterol level, have developed more
favourably in women (Vartiainen et al. 1994(a)) and in our study, the improvement in
subjective health was more pronounced among women. The prevalence of back pain,
however, decreased among men but not among women.
Among men, the more positive development in self-rated health in North Karelia than in
Kuopio Province between 1972 and 1982 might reflect the effect of the community-
based cardiovascular disease prevention project carried out in North Karelia since the
beginning of the 1970s. Smoking, serum cholesterol, and blood pressure also decreased
more in North Karelia during the same period of time (Vartiainen et al. 1994(a))
reflecting the fact that the whole population of North Karelia was exposed to the
community program (Puska et al. 1995). Additionally, the prevalence of back pain was
45
reduced in North Karelia more than was the case in Kuopio Province during the same
period of time (Heistaro et al. 1995).
7.3 Health and socioeconomic background
Our results point to a strong association between education and health, which is in
accordance with earlier studies (Lahelma et al. 1994, Pincus and Callahan 1994).
However, among men, the educational differences in self-rated health diminished during
the period 1972-1992, which is concordant with other Finnish studies (Lahelma et al.
1997(a), Lahelma et al. 1997(b)).
The division into subgroups by education that we used is not totally unproblematic,
though we avoided many biases by classifying the subjects according to their birth years.
The overall educational level of the Finnish population improved decisively during the
second half of the 20th century, which brings persons with a wide variety of school years
into the same educational group. Instead of assessing school years, another possibility
would be to sort by “only basic education”, “high school or vocational education”, and
“university degree”. This would cause difficulties as well, again due to the improvement
in the average educational level of the population. The method we used has obvious
advantages since we were interested in one individual’s social position in relation to
others.
Household income is not as personal an indicator as education. Yet household income is
a better indicator in certain cases than personal income, e.g. the unemployed and
housewives.
There has been a considerable improvement in the standard of living in Finland during
the past decades. Heavy physical work has changed to lighter work, standards of housing
have improved, people have more free time and can pay more attention to other things
above just earning their living. Nowadays people are well aware of and interested in
health and health-related items. These social changes may also contribute to how people
are feeling about their health. On the other hand, one could assume current health
expectations to be higher than earlier.
46
Socioeconomic status had a marked inverse relationship also with the prevalence of back
pain. This is concordant with the results of several earlier studies (Morrell 1972, Nagi et
al. 1973, Gyntelberg 1974, Croft and Rigby 1994).
7.4 Self-rated health and its association with mortality
Self-rated general health improved clearly in both sexes during the follow-up 1972-
1992. Comparing these trends with other available studies on the subject (Lahelma et al.
1997(a), Lahelma et al. 1997(b), Arinen et al. 1998), our results show a slightly more
positive development in self-rated health. The other studies, however, do not have data
from the early years of the 1970s, and the materials, like the age range, vary between the
studies. In our study, women reported better general health than men, as expected based
on earlier results (Lahelma et al. 1997(a)).
Self-rated health strongly predicted mortality in the randomly selected population
cohort in eastern Finland. This association was only partly explained by medical
history, cardiovascular disease risk factors, and education. The relationship was strong
among both men and women, and it was evident during the short-term as well as the
longer follow-up period. A clear gradient was found from “good” through “average” to
“poor” self-rated health in relation to all-cause and cardiovascular mortality.
These results are in line with several earlier studies published in recent years (Mossey
and Shapiro 1982, Kaplan and Camacho 1983, Idler et al. 1990, Idler and Kasl 1991,
Wannamethee and Shaper 1991, Pijls et al. 1993, Grant et al. 1995, Appels et al. 1996,
Kaplan et al. 1996(b), Idler and Benyamini 1997, Miilunpalo et al. 1997, Sundquist and
Johansson 1997, McGee et al. 1999, Burström and Fredlund 2001, Martikainen et al.
2002), in other words, self-rated health is associated with subsequent mortality even
when the models are adjusted for several background variables.
The specific advantages of the present study were its large samples sizes, the wide age
range of the cohort, the long follow-up with two assessment points, reliable links with
the mortality register, detailed data on causes of mortality, data on several self-reported
medical history items, and measured cardiovascular disease risk factors (objective
indicators of health in addition to self-reported data).
47
It has been suggested that the predictive value of self-rated health could be partly
caused by a “healthy attitude” to life: an individual attempts to achieve that high level
of health that the individual has chosen (Idler and Kasl 1991, Cott et al. 1999). Thus
self-rated health may reflect the level of life control (Bobak et al. 2000). It may also
indicate the respondent’s personal, possibly unconscious, assessment of his or her life
expectancy (Idler and Kasl 1991) taking into account all that he or she knows to have an
effect on health and mortality. The association between self-rated health and external
causes mortality could be partly explained by some kind of risk taking behaviour.
Self-rated health is a unique tool for population surveys (Miilunpalo et al. 1997, Manor
et al. 2001), although we do not yet fully understand all that it constitutes and the ways
through which it is associated with future health events. The predictive power of self-
rated health confirms the importance of reports of subjective health, i.e. what people say
about themselves to health professionals.
The analyses in the further analyses section were in line with earlier findings that self-
rated health is a complex issue associated with several dimensions of health, such as
diagnosed diseases and symptoms (Leinonen et al. 2001(b), Reyes-Gibby et al. 2002) as
well as health behaviour (Johansson and Sundquist 1999, Poikolainen and Vartiainen
1999) and body mass index (Okosun et al. 2001). The changes in the selected
determinants of self-rated health could explain only a part of the observed improvement
in self-rated health during 1972-1992.
In our models in the further analyses section, all the variables were adjusted for each
other (Table 3), which may cause some overlap due to collinearity, for example self-
reported blood pressure diagnosed or treated by a doctor, and measured blood pressure.
This may lead to an underestimation of the associations of both variables with self-rated
health.
However, with this model we could assess independent associations of the variables
with self-rated health. For example, in the case of blood pressure, we could evaluate the
strength of the risk factor itself as a determinant of poor self-rated health, independent
of whether the person knew whether he or she had this diagnosed disease. Many of the
48
psychosomatic symptoms may also have common background factors with each other.
7.5 Back pain
Nearly half of the study population reported that they had experienced back pain during
the preceding month. During the 20 years of follow-up, a slight fall in the back pain
prevalence was observed among men, while the prevalence remained stable among
women. Our results are in line with earlier publications on trends in the prevalence of
back pain in Finland (Leino et al. 1994, Manninen et al. 1996). Generally, the prevalence
rates seemed to differ considerably between subgroups of the population. Back pain was
also an important contributor to self-rated general health.
The consistency of replication can be considered a central criterion in testing
epidemiologic evidence of disease causation. A causal association should remain stable
in time within a given study design. The present study, thus, not only offered a unique
opportunity to compare time trends in the occurrence of back pain between population
groups, but also to test the stability of the associations between back pain and its
suspected risk factors.
Low education, blue-collar occupations, and physical load at work had strong and time-
stable associations with back pain among both sexes. Furthermore, stability was also
noted in the way that back pain was associated with body mass index among women and
with smoking among men. The differences according to household income diminished
between 1972 and 1992 among both sexes.
Associations between smoking and back pain have consistently been found in a number
of studies (Frymoyer et al. 1983, Deyo and Bass 1989, Heliövaara et al. 1991, Ernst
1993, Croft and Rigby 1994, Goldberg et al. 2000). The results of the present study are
in line with the previous observations. In women, however, the association between
smoking and back pain only became apparent towards the end of the study period, but
even then female ex-smokers had the highest prevalence rates of back pain. In the early
surveys, however, the female ex-smoker category was rather small, which may explain
the sudden changes in this category.
49
7.6 Comparing North Karelia and Pitkäranta
Our study showed that unequivocal subjective health differences exist between the
eastern province of North Karelia, Finland, and Pitkäranta in the Republic of Karelia,
Russia, mostly in favour of eastern Finland. Self-rated health was considerably better in
North Karelia than in Pitkäranta. High household income and education were associated
with good self-rated health in North Karelia, and in women but not men in Pitkäranta.
Self-reported physical condition was better in North Karelia than in Pitkäranta, and
psychosomatic and many somatic symptoms were more prevalent in Pitkäranta.
However, potential cultural differences in these self-reports on health must be taken into
account.
The observed health disparities between the areas may result directly from the more
unfavourable health behaviour and/or the higher cardiovascular or other disease
morbidity in the Republic of Karelia. The health gap between the two areas represents a
challenge for disease prevention and health promotion activities. Some slight
improvement in the risk factor profile in the Republic of Karelia has already occurred
(Laatikainen et al. 2002).
50
51
8. CONCLUSIONS
Self-rated health improved considerably in Finland between 1972 and 1992. The
development was more favourable for women than for men. Socioeconomic factors,
namely education and household income, were unequivocal indicators of good
subjective health status. Among men, but not among women, their importance as
predictors of good health, however, diminished during the 20-year period.
We also found a slightly decreasing trend in the prevalence of back pain among men.
The prevalence rates seemed to differ considerably between subgroups of the population.
However, the trends varied markedly between the categories of some suspected risk
factors for back pain, such as overweight and leisure-time physical activity.
In North Karelia, Finland, people not only have lower mortality but also feel healthier
than people across the border in the neighbouring region in the Republic of Karelia,
Russia. Socioeconomic differences in subjective health were less clear in the Republic
of Karelia.
Self-rated health was a strong predictor of mortality in a randomly selected population
cohort in eastern Finland, and its predictive power was only partly explained by a
variety of items from the medical history, cardiovascular disease risk factors, and
education. This association existed among both sexes for all-cause and cardiovascular
mortality and, especially among men, for mortality due to external causes. A clear
gradient was found from “good” through “average” to “poor” self-rated health in
relation to all-cause and cardiovascular mortality.
The health gap between North Karelia and the Pitkäranta area in Russian Karelia is a
challenge for effective disease prevention and health promotion activities. Since the
health gap concerns a broad range of health problems, comprehensive health promotion
is clearly needed. The effective heart health intervention aimed at changing unhealthy
lifestyles in North Karelia has been accompanied by a general improvement in the
health of the population (Puska et al. 1998).
The goal for health promotion in the industrialised world has been to increase the
52
number of healthy years, which means postponing the age-related diseases into later
years of life while simultaneously increasing life expectancy. Our results give
indications that when objective health status improves people also actually feel healthier.
53
9. ACKNOWLEDGEMENTS
The present study was carried out in the Department of Epidemiology and Health
Promotion and in the Department of Health and Disability at the National Public Health
Institute (KTL). I gratefully acknowledge the National Public Health Institute for
providing such an exceptionally stimulating environment and excellent facilities for my
research.
I express my deepest respect and gratitude to my supervisors, Professor Pekka Puska,
MD, PhD, MPolSc, and Professor Erkki Vartiainen, MD, PhD, for their endless
encouragement and support throughout this study, and for introducing me to this
fascinating field of research.
The official referees of my thesis were Docent Ossi Rahkonen, PhD, from the
Department of Social Policy in the University of Helsinki, and Professor Jussi
Kauhanen, MD, PhD, from the Department of Public Health and General Practice in the
University of Kuopio. I gratefully thank them for their expert review of the manuscript
and for their constructive criticism.
I warmly thank my co-authors, Dr. Markku Heliövaara, MD, PhD, Dr. Tiina
Laatikainen, MD, PhD, Dr. Antti Uutela, PhD, and Dr. Pekka Jousilahti, MD, PhD,
from the National Public Health Institute; Professor Eero Lahelma, PhD, from the
Department of Public Health in the University of Helsinki; and Dr. Mihail Uhanov,
MD, and Dr. Svetlana Pokusajeva, MD, from the Central Hospital of Pitkäranta, for
excellent co-operation and valuable advice during my work.
To Professor Arpo Aromaa, MD, PhD, the Director of the Department of Health and
Disability, I provide a special acknowledgement for continuous support and for
valuable comments during the preparation of my thesis.
I express my sincere thanks to the entire personnel of the Department of Health and
Disability and of the Department of Epidemiology and Health Promotion for creating a
friendly and inspiring atmosphere for my work during all these years.
54
Furthermore, I would like to thank Dr. Ewen MacDonald, PhD, who revised the
language of the final manuscript of this thesis.
My dearest thanks I wish to express to Ms. Annamari Kilkkinen, MSc, for her endless
support and help. Finally, my warmest thanks to all my family members and to my
friends for always encouraging me in my work.
Helsinki, October 2002
Sami Heistaro
55
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