Objectives　This study aimed to determine risk factors for frailty and lifestyle-related diseases impacting the incidence of loss of independence among Japanese community-dwelling older adults, and to measure the magnitude of these associations.Methods　We conducted an 8.1-year prospective study involving 1,214 residents of the town of Kusatsu, aged 65 years and over, who were initially free of disability and underwent the comprehensive geriatric assessment between 2002 and 2011. Loss of independence was defined as the incidence of disability or having died before the occurrence of disability was certified by the Long-Term Care Insurance program in Japan. Risk factors for lifestyle-related diseases and health status comprised hypertension, diabetes mellitus, overweight, chronic kidney disease, current smoking, past history of stroke, heart disease and cancer, frailty, underweight, anemia, hypoalbuminemia, and cognitive decline. Frailty was defined as the presence of three or more of the following criteria: Weight loss, weakness, exhaustion, slowness, and low levels of physical activity. Prefrailty was defined as the presence of one or two of these same criteria. Cox proportional-hazard regression model was used to estimate hazard ratios (HR) and the population attributable fraction (PAF) of loss of independence.Results　During the follow-up, 475 cases, including 372 disabilities and 103 deaths, were identified as having experienced loss of independence. The multivariable HRs for the loss of independence were 1.3 to 2.2-fold higher for the presence of frailty, past history of stroke, cognitive decline, prefrailty, and smoking. The PAF of loss of independence was the greatest for prefrailty (19%), followed by frailty (12%). The PAF was relatively large for prefrailty (19%) and smoking (11%) in men, and frailty (18%), prefrailty (18%), and chronic kidney disease (11%) in women. Stratified by age category, participants aged 65-74 years having frailty and several lifestyle-related diseases showed significantly higher HRs for loss of independence and greater PAFs for prefrailty (18%), frailty (13%), and smoking (11%).Conclusions　Loss of independence among Japanese community-dwelling older adults who underwent screening examinations was largely attributed to frailty and prefrailty. Our findings suggest that the screening and the intervention for frailty and lifestyle-related diseases in the early stages of old age might be beneficial in prolonging healthy life expectancy of Japanese community-dwelling older adults.

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