Author:
Brilleman Samuel L,Pachana Nancy A,Dobson Annette J
Abstract
Abstract
Background
There are well-established risk factors, such as lower education, for attrition of study participants. Consequently, the representativeness of the cohort in a longitudinal study may deteriorate over time. Death is a common form of attrition in cohort studies of older people. The aim of this paper is to examine the effects of death and other forms of attrition on risk factor prevalence in the study cohort and the target population over time.
Methods
Differential associations between a risk factor and death and non-death attrition are considered under various hypothetical conditions. Empirical data from the Australian Longitudinal Study on Women's Health (ALSWH) for participants born in 1921-26 are used to identify associations which occur in practice, and national cross-sectional data from Australian Censuses and National Health Surveys are used to illustrate the evolution of bias over approximately ten years.
Results
The hypothetical situations illustrate how death and other attrition can theoretically affect changes in bias over time. Between 1996 and 2008, 28.4% of ALSWH participants died, 16.5% withdrew and 10.4% were lost to follow up. There were differential associations with various risk factors, for example, non-English speaking country of birth was associated with non-death attrition but not death whereas being underweight (body mass index < 18.5) was associated with death but not other forms of attrition. Compared to national data, underrepresentation of women with non-English speaking country of birth increased from 3.9% to 7.2% and over-representation of current and ex-smoking increased from 2.6% to 5.8%.
Conclusions
Deaths occur in both the target population and study cohort, while other forms of attrition occur only in the study cohort. Therefore non-death attrition may cause greater bias than death in longitudinal studies. However although more than a quarter of the oldest participants in the ALSWH died in the 12 years following recruitment, differences from the national population changed only slightly.
Publisher
Springer Science and Business Media LLC
Subject
Health Informatics,Epidemiology
Reference14 articles.
1. de Graaf R, Bijl RV, Smit F, Ravelli A, Vollebergh WA: Psychiatric and sociodemographic predictors of attrition in a longitudinal study: The Netherlands Mental Health Survey and Incidence Study (NEMESIS). Am J Epidemiol. 2000, 152: 1039-47. 10.1093/aje/152.11.1039.
2. Gray R, Campanelli P, Deepchand K, PrescottClarke P: Exploring survey non-response: The effect of attrition on a follow-up of the 1984-85 health and life style survey. Statistician. 1996, 45: 163-183. 10.2307/2988406.
3. Slymen DJ, Drew JA, Elder JP, Williams SJ: Determinants of non-compliance and attrition in the elderly. Int J Epidemiol. 1996, 25: 411-9. 10.1093/ije/25.2.411.
4. Eaton WW, Anthony JC, Tepper S, Dryman A: Psychopathology and Attrition in the Epidemiologic Catchment-Area Surveys. Am J Epidemiol. 1992, 135: 1051-1059.
5. Kalton G, Lepkowski J, Montanari GE, Maligalig D: Characteristics of second wave nonrespondents in a panel survey. Proceedings from the Survey Research Methods Section. 1990, Alexandria, VA: American Statistical Association, 462-467.
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