Association between intra-household isolation and frailty among community-dwelling older adults in Japan: A cross-sectional analysis of the Wako Cohort Study

BACKGROUND: Frailty is a growing public health concern, with emerging evidence highlighting the importance of social determinants, including external and intra-household isolation. This study examined the association between intra-household isolation and frailty among community-dwelling older adults in Japan and explored whether external social connections modified this association. METHODS: Data were obtained from the 2023 baseline survey of the Wako Cohort Study, including 6,429 participants aged ≥65 years in Wako City, Saitama Prefecture, without long-term care certification levels 3-5 (men: 45.0%; mean age: 76.5 years). Intra-household isolation was defined as living with others but having minimal interaction (talking