Joint trajectories of physical frailty and social relationships and associated long-term care needs among Japanese community-dwelling older adults: a 6-year longitudinal study
摘要
Physical frailty and social relationships are key factors in older adults’ health. However, their joint trajectories and associations with long-term care needs remain unclear. This study aimed to identify joint trajectories of physical frailty and social relationships among Japanese community-dwelling older adults and evaluate their association with long-term care needs.
MethodsThree waves of data were collected between 2014 and 2020 in suburban Japan. Of 1,004 older adults aged ≥ 65 years, 704 initially independent participants with at least two waves of data were included in the analysis. Physical frailty was assessed using the physical strength dimension of the Kihon Checklist. Social relationships were evaluated by Index of Social Interaction, and joint trajectories were identified using parallel process latent class growth models. The associations between trajectories and long-term care needs were examined by Kaplan–Meier survival curves and Cox proportional hazard regression models. Several sensitivity analyses were conducted to ensure the findings to be robust, including multiple imputations for missing covariates, propensity score matching to address potential bias due to high dropout rates in wave 3, and Fine-Gray competing risk models for considering the competitive risk of mortality.
ResultsThree dual trajectories were identified: low frailty and high social relationships (78.0%), progressive frailty and maintenance of social relationships (14.8%), and progressive frailty and rapid social relationships decline (7.2%). Over the 6-year follow-up, 103 participants required long-term care. Kaplan–Meier analysis revealed significant differences in independence rates among groups (log-rank P < 0.001). Compared to the low frailty and high social relationships subgroup, the progressive frailty and maintenance of social relationships subgroup exhibited a 133% higher risk of requiring long-term care (adjusted HR: 2.33, 95% CI: 1.33–4.06), whereas the progressive frailty and rapid social relationships decline subgroup had a 285% higher risk (adjusted HR: 3.85, 95% CI: 2.05–7.22). The results of the sensitivity analysis confirmed these associations.
ConclusionsThere are distinct joint trajectories of physical frailty and social relationships among Japanese community-dwelling older adults. These trajectories are associated with different risks of long-term care needs, with the progressive frailty and rapid social relationships decline subgroup facing the greatest burden.