Résumé :
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[BDSP. Notice produite par INIST-CNRS 9F9kmR0x. Diffusion soumise à autorisation]. Background : Selection bias in observational epidemiology-the notion that people who participate in a study are fundamentally different from those who do not-is a perennial concern. In cohort studies, a potentially important but little investigated manifestation of selection bias is the distortion of the exposure-disease relationship according to participation status. Methods : Seven years after the original UK Health and Lifestyle Survey (HALS1 ; N=6484), attempts were made to resurvey participants (HALS2). The baseline characteristics, mortality experience following the completion of HALS2 and, finally, the baseline risk factor-cardiovascular disease (CVD) mortality gradients in HALS2 non-participants (N=1894) and participants (N=4590) were compared. Results : Resurvey non-participants, based on data from HALS1, were younger, were of lower social class and had a lower prevalence of hypertension or self-reported limiting long-standing illness, but a higher prevalence of psychological distress (p=0.108). Conclusion : In the present cohort study, non-response at resurvey did not bias the observed associations between baseline risk factors and later CVD mortality. Future studies should also examine the impact of non-response to baseline surveys on these relationships.
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