Effect of Sarcopenia Status on Disability Incidence Among Japanese Older Adults

The updated definition of sarcopenia by the European Working Group on Sarcopenia in Older People (EWGSOP2) recommends both low muscle mass and quality to diagnose sarcopenia; concurrent poor physical performance is considered indicative of severe sarcopenia; however, the relationship between the revised definition and disability incidence among Japanese older adults is unclear. Therefore, we aimed to examine the associations between EWGSOP2-defined sarcopenia and disability incidence among community-dwelling older Japanese adults.

Nationwide study.

We included 4561 individuals aged ≥65 years and enrolled in the National Center for Geriatrics and Gerontology-Study of Geriatric Syndromes (NCGG-SGS).

Skeletal muscle mass was assessed using a bioimpedance analysis device; handgrip strength and walking speed were measured as physical performance indicators. We used the Asian Working Group for Sarcopenia cutoffs to define low muscle mass and poor physical performance. We stratified all participants into nonsarcopenia, sarcopenia, and severe sarcopenia groups. Disability incidence was prospectively determined over 49 months using data extracted from the Japanese long-term care insurance system.

The prevalence of sarcopenia and severe sarcopenia was 3.4% and 1.7%, respectively. Participants with any form of sarcopenia were at a higher risk of disability [hazard ratio (HR) 1.78, 95% confidence interval (CI) 1.27-2.49]. Although participants with severe sarcopenia showed a higher risk of disability (HR 2.00, 95% CI 1.32-3.02), there was no significant disability risk in the sarcopenia group (HR 1.54, 95% CI 0.97-2.46). Grip strength (HR 0.96, 95% CI 0.94-0.98) and walking speed (HR 0.19, 95% CI 0.12-0.30) negatively correlated with disability incidence.

Severe sarcopenia, involving low muscle mass and poor physical performance, might increase disability risk in older adults, as opposed to low muscle mass alone. Further studies are needed to determine whether sarcopenia without poor physical performance increases disability risk.