What kills us?: Yesterday, today &

tomorrow

How much have mortality patterns changed and why?

R.Fielding

Learning objectives• Define incidence, prevalence,

morbidity and mortality

• Give examples of major ratios used to define morbidity and mortality

• Describe changes in cause of death in HK over the past century

• Give valid explanations for these changes

Learning objectives

• Describe the allocation of mortality to different categories of biology, environment, lifestyle, health care and contrast this with the expenditure in these areas;

• Describe the major determinants of health at the community level

Definitions• Morbidity: all ill-health, sickness, etc.• Mortality: all deaths.• Incidence: (number of new cases of a

disease) / (popn. at risk) per unit time.• Prevalence: all cases (new and old) of a

disease/ total population per unit time.• Ratio: proportion of those affected relative

to a given unit of population or events

Common ratios• Mortality rate: Number of deaths per unit

of population (10,000 or 100,000)• Infant Mortality Rate:

deaths among children < 1 year old total number of children < 1 year.

• Standardized Mortality Ratio (SMR): product of (number of observed deaths x100)/(number of expected deaths). >100 indicates excess deaths, < 100 indicates a lower mortality.

Leading causes of death, HK.

1912 1948 1993Plague 379 Pneumonia 175 Cancer 9,311T.B. 239 T.B. 109 Heart 4,707Pneumonia 238 Enteritis 98 CVD 3,247Smallpox 121 Perinatal 67 Pneumonia 2,209Paralysis /convulsion

119 Ill-defined 45 Accident 1,694

Malaria 92 Violence 43 Nephritis 851Diarrhoea 82 Heart 32 Septicemia 560Developmtl 81 Cancer 22 Liver 498Old age 76 G.U. 19 Bronchitis 436Unknown 71 Digestive 18 Diabetes M. 425

(TB) 396rate/1,000 7.8 (0.414) 5.04

Expectation of life at birth, men, 1871-1971 (UK)

1871

1931

1901

1961

35

40

45

50

55

60

65

70

75

80

life expectancy

trend

Age-standardized annual mortality rates 1851-1930 (UK)

100

1,000

10,000

'51 '61''71'81 '91 '01 '11 '21

TB

B, P, I

Whoopingcough

Measles

Epidemiological model for disease evaluation

% allocation of mortality

% ofdeaths

Cause ofmortality

medicalcare

Lifestyle

Environment

Biology

34.0 Heart dis. 12 54 9 2814.9 Cancer 10 37 24 2913.4 CVD 7 50 22 218.0 Accident 13 60 25 23.8 Influenza

pneumon18 23 20 39

2.7 Respiratory 13 40 24 24

Comparison of US Federal expenditure to allocation of mortality according to

epidemiological model

Epidemiologicalmodel

Federal healthexpenditure1974-1976 (%)

Allocation ofmortality (%)

System ofmedical careorganization

90.2 11

Lifestyle 1.3 43

Environment 1.6 19

Human biology 6.9 27

Questions1. How has mortality changed in HK

since 1900?

2. Why have these changes occurred?

3. What does this tell us about the important influences on mortality?

4. How should we be spending our health budget?

1. How has the pattern of mortality changed?

• From acute to chronic degenerative causes and (in children and younger adults) accidents.

• Life expectancy at adulthood little changed, but childhood survival improved during last 100 years.

How has mortality changed? (cont.)

• Infectious disease mortality declined before causes (and Rx) were identified, –so medical interventions not

responsible–what else happened in Europe

1830-1930 and HK 50 years later?

2. What has contributed to these changes? (a)

• Changes in the nature of work

• Food hygiene laws, improved income => better nutrition

• Infrastructure development =>–better living conditions

–clean drinking water

–sewage disposal

2. What has contributed to these changes?(a)

• Decline in fertility rate altered family size, birth spacing and age distribution; =>

• increase in median age of infection and lower case fatality rate; =>

• More children survived, so the mean age of the population increased.

Expectation of life at birth, men, 1871-1971 (UK)

1871

1931

1901

1961

35

40

45

50

55

60

65

70

75

80

life expectancy

trend

2. What has contributed to these changes?(b)

• From W.W.II onwards change in activity levels: less manual labour more motorized transport.

• Increases in

– disposable income– food availability & marketing strategies– dietary and other substance intake

2. What has contributed to these changes?(b)

• Increase in body mass (DM, CHD, HT)

• Tobacco / alcohol use / environmental degradation > rise in chronic disease prevalence.

• Economic developments, loss of control, competitiveness.

3. What does this tell us about important influences on mortality?• Improvements in life expectancy

small despite massive expenditure on health care delivery.

• Most mortality declines due to economic, cultural, behavioral and domestic changes

• Societal, cultural and behavioural influences have been more important that medical care.

4. How should we be spending our health budget to improve health further?

• Many current causes of mortality incurable.

• Prevention best approach to further reductions in mortality

• Economic and occupational improvements are among most important developments.

• Environmental degradation (consumer behaviour) is now most important threat.

Mortality from coronary heart disease, men (20-64) UK

0 50 100 150 200 250 300

Unskilled

Part skilled

Skilled m

Skilled nm

Managerial

Professional

European age-standardized mortality rate/100,000

Conclusions

• Economic/political, social & individual behaviour impacts on environment and behaviour, disturbing systemic homeostasis (ecosystem),

• result is increased risk exposure and heightened vulnerability.

Conclusions• Mortality primarily influenced by socio-

economic factors through opportunity and personal behaviour.

• Future declines in mortality will derive mostly from social-level changes (e.g. legislation on drink-driving, smoking, pollution, education) and personal behaviour.

• Preventive measures offer better value for money.