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[Selection effects in epidemiological cohorts: nature, causes and consequences].
1INSERM Unité 88, 14, rue du Val d'Osne, 94415 Saint-Maurice Cedex, France.
Revue D'Epidemiologie Et De Sante Publique
|February 15, 2002
Summary
Selection effects in cohort studies can bias results. The healthy worker effect in industrial cohorts and volunteer bias in other studies impact disease and exposure estimations.
Area of Science:
- Epidemiology
- Biostatistics
Background:
- Selection effects arise when study populations differ from target populations due to subject inclusion or follow-up.
- These effects can bias estimates of disease frequency, exposure prevalence, and disease-exposure associations.
Purpose of the Study:
- To describe the components of selection effects in cohort studies.
- To examine the consequences of these effects on study outcomes.
Main Methods:
- Review of selection mechanisms in cohort studies.
- Analysis of bias introduced by subject inclusion and follow-up.
Main Results:
- Industrial cohorts exhibit the 'healthy worker effect,' where employment status is linked to health and lifestyle.
- Volunteer cohorts may have selection biases related to participation and retention.
- Exposure and health status influence cohort retention, further impacting results.
Conclusions:
- Understanding selection effects is crucial for accurate epidemiological research.
- Both baseline inclusion and longitudinal follow-up contribute to selection bias.
- Mitigating selection bias requires careful study design and analysis.