Mild Cognitive Impairment Predicts Institutionalization among Older Men: A Population-Based Cohort Study

BACKGROUND There is a lack of evidence on the contribution of mild cognitive impairment (MCI) to institutionalization in older adults. This study aimed to evaluate a range of risk factors including MCI of institutionalization in older men. METHODS Men aged ≥70 years (n = 1705), participating in the Concord Health and Ageing in Men Project, Sydney, Australia were studied. Participants completed self-reported questionnaires and underwent comprehensive clinical assessments during 2005-2007. Institutionalization was defined as entry into a nursing home facility or hostel at any time over an average of 5 years of follow-up. Cox regression analysis was conducted to generate hazard ratios (HR) with 95% confidence intervals (CI). RESULTS A total of 125 (7.3%) participants were institutionalized. Piecewise Cox proportional models were generated and divided at 3.4 years (1250 days) of follow-up due to violation of the proportional hazards assumption for the association between MCI and institutionalization (χ(2) = 6.44, p = 0.01). Dementia, disability in Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL), poor grip strength, few social interactions, being a Non-English speaking immigrant and age were predictive of institutionalization during both time periods, whereas MCI (HR = 4.39, 95%CI 2.17-8.87) only predicted institutionalization in the period beyond 3.4 years of follow-up. Being married (HR = 0.42, 95%CI: 0.24-0.72) was protective only during the period after 3.4 years of follow-up. DISCUSSION In this study, the strongest predictors of institutionalization were dementia, MCI, ADL and IADL disability. MCI was not a predictor of early institutionalization but became a significant predictor beyond 3.4 years of follow-up.