Non-response bias in a study of cardiovascular diseases, functional status and self-rated health among elderly men

• Published in: Age and ageing 1998-01, Vol.27 (1), p.35-40
• Main Authors: HOEYMANS, NANCY, FESKENS, EDITH J. M., VAN DEN BOS, GEERTRUDIS A. M., KROMHOUT, DAAN
• Format: Article
• Language: English
• Subjects: Activities of Daily Living - classification; Aged; Aged, 80 and over; Bias; Cardiovascular diseases; Cardiovascular Diseases - epidemiology; Cardiovascular Diseases - psychology; Cerebrovascular Disorders - epidemiology; Cerebrovascular Disorders - psychology; Dementia; Disability Evaluation; Elderly; Elderly men; Factors; Functional assessment; functional status; Geriatric Assessment - statistics & numerical data; Geriatrics; Health risk assessment; Health status; Health status indicators; Health surveys; Humans; Longitudinal Studies; Male; Mathematical statistics; Medical research; Medicine, Experimental; Methods; myocardial infarction; Myocardial Infarction - epidemiology; Myocardial Infarction - psychology; Netherlands; Netherlands - epidemiology; non-respondents; Old age; Patient Dropouts - psychology; Patient Dropouts - statistics & numerical data; Psychological aspects; Quality of Life; Sick Role; Statistical methods; Statistics (Mathematics); Stroke; Stroke (Disease); study design; Surveys; Surveys (Studies)
• ISSN: 0002-0729; 1468-2834
• DOI: 10.1093/ageing/27.1.35

Objectives: to investigate to what extent differences in health status between respondents and drop-outs affected the associations between cardiovascular diseases and functional status and self-rated health in a population-based longitudinal health survey in elderly men. Methods: during the 1993 survey of the Zutphen Elderly Study, a non-response survey was carried out. The prevalence of myocardial infarction and stroke, disabilities in basic activities of daily living (BADL) and mobility, and self-rated health were compared between non-respondents (n = 99) and respondents (n = 381). Associations between myocardial infarction and stroke on the one hand and functional status and self-rated health on the other were calculated for the total population and for the respondents to assess the amount of under- or overestimation of these associations. Results: the health of non-respondents was worse than that of respondents in terms of stroke, disabilities in BADL and mobility and self-rated health. Due to this selective non-response, the associations between cardiovascular diseases and functional status and self-rated health were biased. Although most of the associations were slightly overestimated, the most important bias was the underestimation by 57% of the association between stroke and disabilities in BADL [total population: odds ratios (OR) = 6.1, 95% confidence interval (CI) = 2.7−13.9; respondents only: OR = 2.6, CI = 0.7–9.9]. Conclusion: selective non-response might lead to bias in the prevalence of disease, disabilities and self-rated health as well as in the associations between disease and functional status and self-rated health. The direction and magnitude of this bias varies according to type of disease and health outcome and is therefore difficult to predict. The need to minimize non-response and to investigate its implications is recommended in every study.