Cognitive frailty as a predictor of dementia among older adults: A systematic review and meta-analysis.

Objective: The aim of this systematic review and meta-analysis was to synthesize the pooled risk effect and to determine whether cognitive frailty is a predictor of dementia among older adults.

Design: Systematic review and meta-analysis. Setting and participants: PubMed, EMBASE, Web of Science, and the Cochrane Library were systematically searched until June 5, 2019. Only cohort studies and population-based longitudinal studies published in English were eligible. Study selection, data extraction and quality assessment of including studies were independently completed by two researchers. A fixed-effects model was used to synthesize the risk of baseline cognitive frailty on dementia in the older adults compared with older adults without cognitive frailty. Measurements: The risk of cognitive frailty on incident dementia.

Results: Of the 1566 identified records, 7 studies met the inclusion criteria and were included in the review. And 4 studies reporting hazard ratio (HR) of incident dementia for cognitive frailty were included in the meta-analysis. Synthesized results showed that baseline cognitive frailty in the elderly was significantly associated with an increased risk of developing dementia as compared with those without cognitive frailty (prefrailty + CI model: pooled HR = 3.99, 95 %CI = 2.94-5.43, p < 0.00001, I2 = 31 %; frailty + CI model: pooled HR = 5.58, 95 %CI = 3.17-9.85, p < 0.00001, I2 = 0 %). Heterogeneity across the studies was low.

Conclusion: Cognitive frailty is a significant predictor of dementia. Cognitive frailty status may be a novel modifiable target in identification of early signs before dementia.