Cognitive Frailty as a Risk Factor for Incident Disability During Late Life: A 24-Month Follow-Up Longitudinal Study.

Tsutsumimoto, K; Doi, T; Nakakubo, S; Kim, M; Kurita, S; Ishii, H; Shimada, H

OBJECTIVES Association between cognitive frailty as identified by a new operational definition and incident disability in the community setting remains unclear. This will be the catalyst for preventive interventions designed to treat adverse health problems among elderlies. DESIGN A 24-month follow-up longitudinal study on a community-based cohort. SETTING Community-setting. PARTICIPANTS Participants included a total of 9,936 older adults aged 65 years or older. MEASUREMENTS Frailty was characterized as slow walking speed or/and muscle weakness represented by grip strength. Cognitive function was assessed according to several tests. Cognitive impairment was defined below the age-education reference threshold. Participants were categorized into the four groups: robust, cognitive impairment alone, frailty alone, and cognitive frailty (both frail and cognitive impairment). Incident disability data was extracted from the Japanese Long-Term Care system. RESULTS The prevalence of cognitive frailty was 11.2%. The cumulative incidence rates of incident disability in each group were also estimated (robust, 9.6/1,000 person-years (95% CI 7.9 to 11.7); cognitive impairment, 21.3/1,000 person years (95% CI 16.3 to 27.7); frailty, 45.4/1,000 person years (95% CI 39.5 to 52.3); and cognitive frailty, 79.9/1,000 person years (95% CI 68.6 to 93.1)). Adjusted Cox proportional hazard model revealed that the cognitive frailty group had the highest hazard ratio (HR 3.86, 95%CI 2.95 - 5.05, P < 0.001). CONCLUSIONS A proper operational definition was developed to determine cognitive frailty among elderlies. Cognitive frailty is more associated with incident disability in community-setting than cognitive impairment or physical frailty alone.