Factors Leading to Institutionalization among the Oldest Old: Longitudinal Findings from the AgeCoDe-AgeQualiDe Study.

Introduction: Due to the strong association between old age and the need for long-term care, the number of individuals in need for care is projected to increase noticeably. The aim of this study was to examine the determinants of institutionalization among the oldest old longitudinally.

Methods: Longitudinal data (follow-up [FU] wave 7-9) were gathered from a multicenter prospective cohort study ("Study on needs, health service use, costs and health-related quality of life in a large sample of oldest old primary care patients [85+]," AgeQualiDe). At FU wave 7, in 2014, complete measures were available for 763 individuals. The average age was 88.9 (standard deviation 2.9) years (range 85-100), and 68% were female. Sociodemographic and health-related independent variables (e.g., depressive symptoms or functioning) were included in the regression model. Institutionalization (admission to assisted living home or nursing home) was used as an outcome measure. Logistic random-effects models were used.

Results: Regressions revealed that among oldest old, the odds of being institutionalized were lower for men (odds ratio [OR] = 0.03; 95% confidence interval [CI] 0.00-0.16). Institutionalization was associated with an increased age (OR = 1.27; 95% CI 1.04-1.55). Additionally, widowed individuals (ref. non-widowed) had higher odds of being institutionalized (OR = 8.95; 95% CI 1.61-49.81). Institutionalization was also associated with functional decline (OR = 0.16; 95% CI 0.11-0.23), whereas it was not significantly associated with cognitive decline, depressive symptoms, and social support.

Conclusion: Our findings stress the importance of gender, age, widowhood, and functional decline for institutionalization among the oldest old. Preventing or at least postponing functional decline might help to delay institutionalization as far as possible.