Social Isolation is Associated with Future Decline of Physical Performance in Community-dwelling Older Adults: a 1-year Longitudinal Study

Background: Social isolation and decline of physical function, such as muscle strength and physical performance, are known to be associated with deterioration of functional capacity. However, the relationship between social isolation and physical function has not been sufficiently clarified by a longitudinal observational study.

Aims: The aim of this study was to examine whether social isolation is associated with a future decline in physical function in older people.

Methods: The participants were 166 community-dwelling older people (aged ≥ 65 years). Social isolation and physical function were assessed using the 6-item Lubben Social Network Scale and handgrip strength, knee extensor strength, usual walking time, and the Timed Up and Go (TUG) test in both the baseline and follow-up surveys. To define the presence or absence of physical function decline over time, we used the minimal detectable change. The associations between social isolation and physical function were analyzed using logistic regression analysis adjusted for confounding factors. Further, to examine the possibility of drop-out bias, inverse probability weighting (IPW) was performed.

Results: The results of the logistic regression analysis adjusted for confounding factors showed social isolation at baseline was significantly associated with future TUG decline (OR 2.88, 95% CI 1.15-7.22). Social isolation was not associated with a decline in other physical functions. Similar results were found in an analysis using IPW.

Conclusions: Social isolation was an independent risk factor for future TUG decline in community-dwelling older people. Our results indicated that assessment of social isolation may be necessary to assess the risk of physical performance decline.