Vascular risk factors for depression and apathy | Part 1 32 Methods Study design and population This study was conducted within the Longitudinal Aging Study Amsterdam (LASA), which is a prospective cohort study of Dutch people aged 55 to 85 years. The LASA started in 1992, and its methods have been described in detail elsewhere 17 18. The general aim of LASA was to study the autonomy and well-being of an aging population. A randomly selected age- and sex-stratified sample (according to expected mortality figures) was drawn from the population registers of 11 municipalities in the Netherlands. The reason for this relative oversampling of older old people (both men and women) and elderly men was to compensate for an anticipated higher unavailability for follow-up among physically frail people. The initial response rate was 62.3%, and nonresponse was associated with age, sex, and urbanicity. The sample first took part in the cross-sectional NESTOR–living arrangements and social networks study 19 and was later interviewed and followed up every 3 years in LASA; 81.7% of the NESTOR–living arrangements and social networks study population participated in LASA, with nonresponse being related to age but not to sex. All interviews were recorded for quality control purposes. All LASA participants without a history of stroke at the baseline measurement were eligible for inclusion (n = 3018). Participants in whom depressive symptoms (51 [1.6%]) or stroke (2 [0.06%]) were not evaluated at baseline were excluded. The remaining 2965 individuals participated in this study of the association among depressive symptoms, CRDSs, or MDD at baseline and incident stroke in patients with or without cardiac disease at baseline. The mean (SD) follow-up was 7.7 (3.1) years; participants were assessed at baseline and every 3 years. For the extended Cox proportional hazards regression analyses, we required the availability of a baseline and at least 1 follow-up assessment of depression. In total, 412 participants (13.9%) were excluded because they had died or had a stroke before the first follow-up interview, and 328 participants (11.1%) were excluded because they never had a follow-up assessment of depressive symptoms. Unavailability for follow-up of depressive symptoms was associated with an older age, a lower score on the Mini-Mental State Examination (MMSE), more functional limitations, and cardiac disease (P < .001 for all). The mean (SD) follow-up for the remaining 2225 participants was 9.1 (1.7) years, with a mean (SD) number of 3.4 (0.8) measurements of depressive symptoms. Measurements Stroke Morbidity and Mortality The study end point was the first occurrence of stroke (fatal or nonfatal). Nonfatal strokes were established based on self-report during the 3-yearly interviews and information obtained from general practitioners (GPs) in response to questionnaires sent in 19921993, 1995-1996, and 2000-2001. The GPs were asked whether a participant had ever been diagnosed as having a cerebrovascular accident, the year in which it occurred, and whether a specialist had confirmed the diagnosis. Previous research in LASA had shown
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