Impact of resurvey non-response on the associations between baseline risk factors and cardiovascular disease mortality: prospective cohort study

• Published in: Journal of epidemiology and community health (1979) 2009-11, Vol.63 (11), p.952-955
• Main Authors: Batty, G D, Gale, C R
• Format: Article
• Language: English
• Subjects: Adult; Alcohol; Baseline studies; Bias; Biological and medical sciences; Blood pressure; Body mass index; Cardiovascular disease; Cardiovascular diseases; Cardiovascular Diseases - etiology; Cardiovascular Diseases - mortality; Censuses; Cohort analysis; Epidemiology; Exercise; General aspects; Health Surveys; Humans; Hypertension; Illnesses; Life Style; Lost to Follow-Up; Male; Medical sciences; Middle Aged; Miscellaneous; Mortality; Participation; Prospective Studies; Public health. Hygiene; Public health. Hygiene-occupational medicine; Questionnaires; Risk Assessment; Risk factors; Selection Bias; Smoking; Social classes; United Kingdom - epidemiology; Womens health
• ISSN: 0143-005X; 1470-2738
• DOI: 10.1136/jech.2008.086892

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⩽0.027). The risk of death from future CVD was significantly higher in those baseline study members who did not participate in HALS2. However, the magnitude of the association between a series of risk factors and CVD mortality was essentially the same in the HALS2 non-participants and participants (p value for interaction⩾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.