Five-year longitudinal study of frailty prevalence and course assessed using the Kihon Checklist among community-dwelling older adults in Japan

Abstract Background: The natural course of scores of the Kihon Checklist, one of the promising tools used for frailty screening, is unknown. We aimed to analyze the 5-year natural course of frailty as assessed using the Kihon Checklist in community-dwelling older adults. Methods: We used the data from the postal Kihon Checklist survey conducted by the municipal government between 2011 and 2016. The sample of the current study consisted of 551 older adults (265 men and 286 women) aged 65-70 years in 2011, who responded to the postal Kihon Checklist both in 2011 and in 2016. A Kihon Checklist score of 0 to 3 was considered an indicator of robustness, 4 to 7 of prefrailty, and 8 or higher of frailty. Group comparisons were performed with significance set at p<0.05. To identify independent risk factors for a transition towards frailty, a logistic regression analysis was performed using factors of p <0.20 in the group comparisons. Results: The median Kihon Checklist score significantly increased from 2 (interquartile range, 1-3) in 2011 to 3 (1-5) in 2016 (p<0.001). Hence, the prevalence of frailty significantly increased from 8.0% to 12.3% (p<0.001) during the same period. Regarding the 5-year transitions in frailty status, the majority (68.3%) of older adults remained unchanged, while 21.4% transitioned towards a worse frailty status, and 10.3% towards an improved status. Of the 507 respondents who were robust or prefrail at the baseline, 44 experienced a transition towards frailty, indicating that the 5-year incidence of frailty was 8.7%. These 44 individuals had higher body mass indexes and lower physical activity scores on the Kihon Checklist than the others (p<0.05). Multivariate analyses demonstrated that the physical activity score of the Kihon Checklist independently predicted a transition towards frailty in 5 years (odds ratio, 1.55; 95% confidence interval, 1.12–2.15; p=0.009). Conclusions: This study was the first to evaluate the course of frailty status, assessed using the Kihon Checklist in community-dwelling elderly adults, and should provide reference data to evaluate the effects of frailty interventions. Additionally, our results suggest that maintaining optimal physical activity should be recommended to prevent transition towards frailty.