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24.05.2010

INTRODUCTION: BACKGROUNG AND JUSTIFICATION Asthma is one of the most common chronic conditions….

Asthma’s possible etiology (adapted from Early life origins of asthma, J. Clin. Invest. James E. Gern, et al. 104:837)

INTRODUCTION: BACKGROUNG AND JUSTIFICATION

(adapted from http://www.european-lung-foundation.org/index.php?id=46)

INTRODUCTION: BACKGROUNG AND JUSTIFICATION

(adapted from http://www.european-lung-foundation.org/index.php?id=46)

Cost of care for asthma in Europe…

The total annual costs of asthma care in Europe amountto approximately €17.7 billion

The recent substantial increase in the reported prevalence of asthma worldwide has led to numerous studies of the

prevalence and characteristics of this condition.

The prevalence of asthma in young adults (20-44 years) in different parts of the Europe (adapted from www.medsci.uu.se)

RESEARCH QUESTION AND AIMS

“What methods exist to assess the prevalence of asthma in Europe?”

The central question that motivates the development of this study is:

And from this main question we can infer three important aims:

- Review the methods used to assess the prevalence of asthma in Europe, that

fit our established inclusion/exclusion criteria;

- Debate the main differences between them and consider advantages and

disadvantages;

- Explore and characterize the 2 major European methods used to assess the

prevalence of asthma, ISAAC and ECRHS.

Participants and methods

STUDY PARTICIPANTS

Our study consisted in a systematic review, therefore we used other articles as unit of analysis in its development.

Inclusion criteria:

- Describe methods to assess the prevalence of asthma;

- Having European population as the assessment target;

- An identifiable description of the methods indicating the sources must

have been present;

- Population-based response rate must have been statistically significant.

Exclusion criteria:

- Articles that have been written before 1990;

- Articles that used a language other than English.

STUDY DESIGN

DATA COLLECTION METHODS - SEARCHING

We searched the MEDLINE with a specific query:

User Query:

asthma AND prevalence AND Europe AND methods AND (Humans[Mesh] AND English[lang])

Query Translation:

("asthma"[MeSH Terms] OR "asthma"[All Fields]) AND ("epidemiology"[Subheading] OR "epidemiology"[All Fields] OR "prevalence"[All Fields] OR "prevalence"[MeSH Terms]) AND ("europe"[MeSH Terms] OR "europe"[All Fields]) AND ("methods"[Subheading] OR "methods"[All Fields] OR "methods"[MeSH Terms]) AND ("humans"[MeSH Terms] AND English[lang])

Results: 1474

KEY-WORDS: Asthma, prevalence, methods, Europe, assessment, ECRHS, ISAAC

DATA COLLECTION METHODS - SELECTING

First selective phase:

Titles and abstracts of the retrieved studies were screened for relevance

each by two reviewers

- concordant in excluding the article would be removed

- concordant in including the article would pass to next phase

If they had not the same opinion it would be necessary a third reviewer…

Second phase:

The full-texts of the articles were analyzed and identified as potentially

relevant through the same review method as the first phase

DATA COLLECTION METHODS - EXTRACTING

Scanning and extracting were conducted on the 28th and 29th of March, 2010.

N=1474

N=1368 articles were excluded

N=106 articles were included

title and abstract scanning

N=24 articles were excluded

N=82 articles were included

full textscanning

DATA COLLECTION METHODS - SYNTHESIZING

After selected articles were obtained a resume was made based on

these pre-established points:

• method name;

• target population;

• year;

• design and structure of the method;

• results obtained;

• possible advantages and disadvantages;

• observations.

VARIABLES DESCRIPTION

We considered two types of variables in our work:

- qualitative- quantitative

Quantitative valuesrepresented by the numerical values obtained in the assessment of the prevalence of asthma by a certain method.

Qualitative valuesrepresented by the nominal values obtained from the characteristics of the methods following the application of the pre-established points.

With all of this we intend to standardize the interpretation of the asthma methods and to better assess their characteristics.

PLANNED STATISTICAL ANALYSIS

Our statistical analysis will consist in:

Descriptive part - describes the general characteristics of a given

method, according to the above mentioned pre-established points.

we will compare extensively all the methods included in the selected articles according to

the pre-established points….

GLOBAL ASSESSMENT ITEMS

Therefore, it is our intention not only to

extensively compare the previously mentioned

characteristics of the different methods found, but

also to consider and reflect on the values obtained by

them.

Special attention will be given to the two major European studies to

assess the prevalence of asthma: ISAAC and ECRHS.

Results

Arnedo-Pena A, Puig-Barberà J, Bellido-Blasco JB, Pac-Sa MR, Campos-Cruañes JB, Artero-Sivera A, Museros-

Recatalá L.

SpainInternational Study of Asthma

and Allergies in Childhood (ISAAC)

2002

Parents of 6-7 year-old schoolchildr

en

Wheeze-8%; asthma-7%;

physician-diagnosed asthma 6%

Allergology Service, Hospital La Paz, Madrid and Center for Biomedical Research in

Respiratory Diseases (CIBER), Spain

Spain Alergológica-2005

between March 2005

and February 2006

Children between 5 and 15 years

The prevalence of asthma was 28%

M F Linehan, M L Hazell, T L Frank, P I Frank Spain ISAAC

In 1993, 1995, 1999, and 2001

1-4 year

72.8%, 70.6%, 65.0%, and

60.7%(1993,1995,1999 and 2001)

L. Garc a-Marcos, A. Blanco Quir , G. Garc a Hern ndez3, F. Guill n-Grima4, C. Gonz lez

D, I. A. Arnedo Pena, R. Busquets Monge, M. Morales

Su rez-Varela, A. L pez-Silvarrey Varela, P. G mez

Cabanillas, J. Batlles Garrido

Spain ISAAC phase I and III

1994–95 (phase I), 2002–2003 (phase III)

children (adolescents

and schoolchildr

en)

10.7%

N. Carvalho, M. Fernández-Benítez, L. Cascante, I. Aguinaga and F. Guillén

Spain ISAAC phases I, II and III

between December 1993 til

September 94

pre-school children 10,6

Author(s) Country Method Year Sample Prevalence

METHODS USED TO ASSESS THE PREVALENCE OF ASTHMA

Articles: 82

Method name Articles

ISAAC - International Study of Asthma and Allergies in Childhood 47

ECRHS - European Community Respiratory Health Survey 06

SIDRIA - Italian Studies of Respiratory Diseases in Childhood and the Environment

03

PMSEAD - Polish Multicentre Study of Epidemiology of Allergic Diseases

01

GNT-HIS - German National Telephone Health Interview Survey 2003

01

Questionnaires (not specified) 23

- Parental questionnaires: 25

- Only questionnaires: 46

- Questionnaires + Clinic Tests: 8

Video: 2

E-mail: 2

Postal: 44

Telephone: 5

In Hospitals: 3

Types of questionnaire - Delivery modes

Discussion/Conclusion


Parental questionnaires: 25

Children may not be able to answer the questionnaires, due to their immaturity, so parental questionnaires are probably a better way to assess asthma in children.

Even though the parents are present, they may not be aware of certain episodes that happen at school or in other occasions in which they were not present.

There may also be lack of communication between the children and the parents.


Only questionnaires: 46

Questionnaires + Clinic Tests: 8

Written questionnaires are probably the method of choice for comparing prevalence in large epidemiological studies, although objective measures may improve the outcome. Clinic tests may provide more exact results. "In a study conducted in 4 different countries only 50 % of the subjects who according to their doctor suffered from asthma reported it in the questionnaire"

TYPES OF QUESTIONNAIRE

• E-mail: 2

• Postal: 44

• Telephone: 5

• Video: 2

• In Hospitals: 3

Postal questionnaires are the most likely to have a higher response rate than the other means of communication.

E-mails require that the target population have Internet at home

Telephone questionnaires require that the target population are at home when the call is made. They are, however, much faster. Telephone questionnaires are answered especially by the retired population and housewives.

Hospital questionnaires have an extremely high response rate, but it is only used when the target population is hospitalized.

ISAAC – INTERNATIONAL STUDY OF ASTHMA AND ALLERGIES IN CHILDHOOD

There are 3 main methods that allow to calculate the prevalence of asthma, using the ISAAC questionnaire:

- written asthma questionnaire

- video questionnaire

- phone interview

Which are the main differences?Advantages and Disadvantages?

VIDEO QUESTIONNAIRE:

- Video questionnaire was developed to try to circumvent the

discrepancies of language.

WRITTEN/POSTAL QUESTIONNAIRE:

The questionnaire were mailed with a pre-paid return envelop.

Those subjects who did not respond within 2 weeks received one reminder letter. After one reminder the overall response rate increased and no further reminders were mailed.

PHONE QUESTIONNAIRE:

- Generally used when no answer is obtained throught written

questionnaire. It is not used as a single method, because it takes to much

time.

ISAAC – WRITTEN QUESTIONNAIRE

Differences between questionnaires completed by parents and

questionnaires completed by children/adolescents:

Parents may report more serious symptoms and they might be less aware of occasional symptoms occurring following exercise.

On the other hand, teenagers may have difficulties in differentiating exercise induced wheezing from other poor conditioning forms of breathlessness that may result in over-reporting.

ISAAC – WRITTEN QUESTIONNAIRE

Women always have greater tendency to answer more easily to this type

of questionnaire, just like older people, because they are usually retired

and/or more available. On the other hand, males and younger people are

lesse available. The latter were, in fact, those who showed a smaller

response rate, probably due to the fact that had no time or patience for

this type of study, eventually find them unnecessary.

Disadvantages:

- phone and mailed questionnaires are not objective

measurements.

VIDEO QUESTIONNAIRE

…participating countries found video prevalence estimates lower than

written estimates for comparable questions.

Why ?

- A possible explanation is that the video scenes are likely to represent more severe symptoms (wheezing at rest) than the written questionnaire, which covers mild to severe symptoms (any wheezing).

- The other possible explanation is not understanding the meaning of the term “wheezing”.

… but there is good agreement between two methods!

Some advantages/disadvantages…

GNT-HIS: GERMAN NATIONAL TELEPHONE HEALTH INTERVIEW SURVEY 2003

Objectives:Estimate of asthma prevalence in German adults based on a

recent nationwide sample and investigate differences according to age, sex, and region of residence (East vs. West) as well as other variables associated with asthma.

Target Population:Non institutionalized adult population 18 years of age and older in

Germany who could be contacted via conventional landline telephone.

Method:First, households were selected with a modified random digit

dialing to reach those with and without a telephone number listed in telephone directories.

Second, the interviewer asked to talk to the household member 18 years of age or older whose birthday was next (next-birthday method).

GNT-HIS: GERMAN NATIONAL TELEPHONE HEALTH INTERVIEW SURVEY 2003

- The questionnaire included only one question on asthma that estimates lifetime prevalence. - The elderly may not remember an asthma diagnosis in younger years or in childhood. This may lead to an underestimation of their lifetime prevalence. - Subjects who participated may differ from non-responders. People who only answered the short questionnaire were significantly older, had a lower educational level, and had better physical health compared to subjects who completed the survey.

Households’ access to landline telephone is not likely to be a significant

problem. According to the Federal Office of Statistics about 98.7% of all German households had a telephone at their disposal in 2004.

Some limitations…

But…

SIDRIA - ITALIAN STUDIES OF RESPIRATORY DISEASES IN CHILDHOOD AND THE ENVIRONMENT

SIDRIA contributed to the ISAAC study with a large sample of children, and widely extended the objective of ISAAC, since it was aimed at evaluating the effects of several potential environmental risk factors, including outdoor air pollution, on children’s respiratory health.

ISAAC(INTERNATIONAL STUDY OF ASTHMA AND ALLERGIES IN CHILDHOOD)

• AIMS:

– Describe the prevalence and severity of asthma, rhinitis and eczema in children living in different centres, and to make comparisons within and between countries;

– Obtain baseline measures for assessment of future trends in the prevalence and severity of these diseases;

– Provide a framework for further etiological research into genetic, lifestyle, environmental and medical care factors affecting these diseases.

ECRHS(EUROPEAN COMMUNITY RESPIRATORY HEALTH SURVEY)

• AIMS:

– Assess the variation in the prevalence of asthma, asthma-like symptoms and bronchial responsiveness in Europe;

– Estimate the variation in exposure to known or suspected risk factors for asthma, to measure their association with asthma and to further assess the extent to which they explain variations in prevalence across Europe;

– Estimate the variation in treatment practice for asthma in the European Community.

ISAAC ECRHS

First such study in children First such study in adults

PHASE I

Comprised a simple standardized questionnaire

Was designed to know the prevalence and severity of asthma and other allergic diseases

worldwide.

Screening questionnaire on asthma symptoms and medication use

PHASE IIWas designed to study etiological factors,

evaluating bronchial hyperactivity

With skin-prick tests to common allergens, measurement of serum total and specific IgE levels, bronchial responsiveness to inhaled methacholine, urine electrolyte levels. An

additional questionnaire on asthma symptoms and medical history, occupation and social status, smoking, the home environment, and use of medications and medical services

PHASE IIIRepetition of phase I, in order to verify the

evaluation of diseases regarding their prevalence

PHASE IVDevelopment and expansion of the scope of the ISAAC website as a resource for ISAAC

collaborators

ISAAC ECRHS

Advantages

The recent development of a standardized written and video questionnaire for self-completion by teenage children offers scope for large scale studies of the prevalence and severity of wheezing illness in both developed and developing countries;

Introduction of any additional variables (geographical, environmental or ethnic) that the country may have incorporated in the questionnaire;

Used with minimal resources in large number of countries worldwide;

Has been validated and has been used to investigate the prevalence of asthma throughout the world. It was used consistent methodology and it was achieved good response rates;

Low cost.

It covers all areas of the European Community and has included other areas also;

Investigators from each of the centres attended a series of training seminars, in which the protocols were explained and the standardized techniques demonstrated. Subsequently, there has been an extensive quality control procedure in the study;

Analysis of the ECRHS II, in which physiological measurements were taken in addition to recording symptoms, may throw more light on these possible effects;

It uses a more objective measure related to asthma: the measurement of bronchial responsiveness (methacholine challenge);

Obtains standardized measurements between areas through the use of challenge testing.

Disadvantages

Has not been validated as a tool for identifying asthma in 1–4 year olds.

Since there are many analyses performed, this survey becomes more expensive.

The effects of language and culture on the reporting of symptoms are a relatively poorly explored area;

Some answers can be misinterpreted, identifying the subject as asthmatic.

REFERENCES

[1] Subbarao, P; Mandhane, P. J; Sears, M. R (2009). Asthma: epidemiology, etiology and

risk factors. DOI:10.1503/cmaj.080612.

[2] Björkstén, B; Dumitrascu, D; Foucard, T; Khetsuriani, N; Khaitov, R; Leja, M; Lis, G;

Pekkanen, J; Priftanji, A; Riikjärv, M.A. (1998). Prevalence of childhood asthma, rhinitis and

eczema in Scandinavia and Eastern Europe. Eur Respir J; 12: 432–437.

[3] Liebhart, J; Malolepszy, J; Wojtyniak, B; Pisiewicz, K; Plusa, T; Gladysz, U. (2007).

Prevalence and Risk Factors for Asthma in Poland: Results From the PMSEAD Study. J

Investig Allergol Clin Immunol; Vol. 17 (6): 367-374.

[4] Burney, P; Chinn, S; Jarvis, D; Luczynska, C; Lai, E. (1996). Variations in the prevalence of

respiratory symptoms, self-reported asthma attacks, and use of asthma medication in the

European Community Respiratory Health Survey (ECRHS). Eur Respir J 9, 687–695.

[5] Urrutia, I; Aguirre, U; Sunyer, J; Plana, E; Muniozguren, N; Martínez-Moratalla, J; Payo, F;

Maldonado, J; Anto, J.(2007). Changes in the Prevalence of Asthma in the Spanish Cohort of

the European Community Respiratory Health Survey (ECRHS-II). Arch

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[6] Caldeira, R. D; Bettiol, H; Bardieri, M A; Terra-Filho, J; Garcia, C A; Vianna, E O (2006).

Prevalence and risk factors for work related asthma in young adults. 63: 694-699.

REFERENCES

[7] Pearce, N; Sunyer, J; Cheng, S; Chinn, S; Bjorksten (2000). Comparison of asthma

prevalence in the ISAAC and the ECRHS. 16: 420-426.

[8] Borrego, M; César, M; Leiria-Pinto, P; Rosado-Pinto, J E. (2005). Prevalence of

asthma in a Portuguese countryside town: repercussions on absenterism and self-

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[9] Priftis, K N; Paragiotakos, D B; Anthracopoulos, M B; Papadimitriou, A; Nicolaidou, P

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[11] Bjerg, A; Standstrom, T; Lundback, B; Ronmark, E (2009). Time trends in asthma

and wheeze in Swedish children 1996-2006: prevalence and risk factors by sex.

ABSTRACTBACKGROUND: Asthma is one of the most common chronic conditions affecting both children and adults, yet much remains to be learned of its etiology. The recent substantial increase in the reported prevalence of asthma worldwide has led to numerous studies of the prevalence and characteristics of this condition. METHODS: We searched the MEDLINE for studies published from 1990 to 2009 which assess the prevalence of asthma in Europe. Using pre-established inclusion and exclusion criteria, we examined as many articles as we could that used European methods to assess the prevalence of asthma, particularly attending to the target population, design and structure of the method, results obtained, as well as possible advantages and disadvantages.

RESULTS: 84 articles describing different studies satisfied our inclusion criteria. 54 of all analyzed studies used the two main European methods, ISAAC (The International Study of Asthma and Allergies in Childhood) – 48 articles - and ECRHS (European Community Respiratory Health Survey) – 6 articles. The remaining 30 were not based in the previous mentioned methods.

CONCLUSIONS: Few well-designed methods have been conducted to assess the prevalence of asthma in European countries. Most European studies are based in ECRHS or ISAAC questionnaires or in their general structure, so that they can overcome their disadvantages. The differences in prevalences are, probably, due to the different existent methods.

Areal, Maria Clara ([email protected]); Ferro, Ana ([email protected]); Horta, Pedro ([email protected]); Mendes, Maria José ([email protected]); Mota, Ricardo ([email protected]);

Pinto, Pedro David ([email protected]); Reis, Ana Clara ([email protected]); Santos, Henrique ([email protected]);

Shekhovtsova, Maria ([email protected]); Silva, Rómulo ([email protected]); Teixeira, Tânia ([email protected]); Vinha,

José ([email protected])

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