Frailty as a Predictor of Alzheimer Disease, Vascular Dementia, and All Dementia Among Community-Dwelling Older People: A Systematic Review and Meta-Analysis

Abstract

Objective: To perform a systematic search of the literature for currently available evidence on frailty as a predictor of dementia and to conduct a meta-analysis to synthesize the pooled risk estimates among community-dwelling older people.

Design: A systematic review and meta-analysis.

Data sources: Embase, MEDLINE, CINAHL Plus, PsycINFO, and the Cochrane Library from 2000 to January 2016, and reference lists of relevant articles.

Eligibility criteria: Any studies that prospectively examined the incident risks of dementia with frailty among community-dwelling older people without language restriction.

Results: Of 2565 studies identified through the systematic review, 7 studies were included in this review. Of these, 4 studies reported hazard ratios (HR) of incident dementia for physical frailty defined by Cardiovascular Health Study criteria and were included in a meta-analysis. Frailty was a significant predictor of incident Alzheimer disease (4 studies: pooled HR = 1.28, 95% confidence interval (95% CI) = 1.00-1.63, P = .05), vascular dementia (2 studies: pooled HR 2.70, 95% CI 1.40-5.23, P = .003), and all dementia (3 studies: pooled HR 1.33, 95% CI 1.07-1.67, P = .01). Heterogeneity across the studies was low to modest (I(2) = 0%-51%). A random-effects meta-regression analysis showed that the female proportion of the cohort primarily mediated the association of frailty with Alzheimer disease (female proportion coefficient = 0.04, 95%CI = 0.01-0.08, P = .01).

Conclusion: This systematic review and meta-analysis suggests that frailty was a significant predictor of Alzheimer disease, vascular dementia, and all dementia among community-dwelling older people. Frail women may have a higher risk of incident Alzheimer disease than frail men.

Keywords: Alzheimer disease; Community-dwelling older people; Frailty; dementia.