Friendship-related social isolation is a potential risk factor for the transition from robust to prefrailty among healthy older adults: a 1-year follow-up study

Purpose Social factors are often overlooked when considering physical frailty. The purpose of this study was to determine whether social isolation is associated with new onset of physical frailty among healthy Japanese older adults. Methods This was a 1-year prospective cohort study conducted in Japan from August 2014 to August 2015. The participants were 229 Japanese older people (106 men, 123 women, mean age = 69.3 +/- 4.2 years) who did not have prefrailty or frailty at baseline and who were current students or graduates of a community college for older people in Japan. Social isolation was assessed using the Lubben Social Network Scale-6 in terms of overall social isolation, family-related social isolation, and friendship-related social isolation. Frailty was categorized using the Fried frailty criteria. The association between new onset of physical frailty and baseline characteristics, including social isolation, was investigated. Results At 1-year follow-up, 180 (78.6%) of the participants remained robust, while 49 (21.4%) were identified as prefrail; no participants were identified as frail. Prefrailty was only associated with friendship-related social isolation (odds ratio: 4.58, 95% confidence interval 2.11-9.92, P < 0.001) at baseline. No significant associations were observed for any other baseline characteristics, including overall social isolation, family-related social isolation, comorbidities, body composition, and physical function. Conclusion Older adults with friendship-related social isolation are four times more likely to develop prefrailty from robust during the 1-year follow-up. The results suggest that friendship-related social isolation increases the risk of healthy older adults transitioning from robust to prefrail. Key summary pointsAim This study concerns an investigation of whether social isolation is associated with the new onset of physical frailty among healthy Japanese older adults. Findings Fourfold higher risk of developing prefrailty during 1-year follow-up. Friendship-related social isolation increases the risk of prefrailty. Message Improving the social isolation of friendship may prevent the transition to frailty.