Social isolation and risk of disability in older adults: Effect modification of metabolic syndrome

Purpose: Delaying the onset of disabilities is a social challenge, especially in an aging society. Social isolation (SI) and metabolic syndrome (MetS) can coexist and pose the risks of disability onset. However, their interaction is not proven in older adults. Therefore, this study investigated whether SI combined with MetS exacerbates disability onset in older adults.Materials and methods: A total of 3,738 community-dwelling older adults underwent a health check-up. After baseline assessments, we followed them up to assess disability incidence for five years. SI was defined as a condition in which two or more of the following measures were met: domestic isolation, less social contact, and social disengagement. MetS was defined according to the criteria of the International Diabetes Federation. We used Cox proportional hazard regression used to identify the interaction effect of SI and MetS on the risk of disability onset after adjusting for potential confounding factors.Results: Multivariate Cox proportional hazard regression showed a significant interaction effect of SI and MetS on disability onset. In the subgroup analysis stratified by MetS status, SI was identified as a risk factor for disability onset only in the MetS group, but not in the non-MetS group.Conclusions: This five-year longitudinal study showed that the co-occurrence of SI and MetS increased the risk of disability onset in older adults. This indicates that the assessment of MetS in socially isolated older adults is important for healthcare providers to delay the onset of disabilities.