Disentangling the Multidimensional Structure of Self-Rated Health: The Predominant Role of Physical Capability in Older Japanese Adults

Background Self-rated health (SRH) is a widely used global health indicator and a strong predictor of morbidity, disability, and mortality in older adults. Unlike objective clinical measures, SRH represents a holistic appraisal of physical, psychological, and social aspects of health. Although prior studies have identified sociodemographic characteristics and multimorbidity as key determinants of poor SRH, the contribution of broader psychosocial and functional dimensions remains unclear. As these domains are typically measured using multiple interrelated indicators, their independent effects are often obscured by redundancy and multicollinearity. To clarify the underlying structure of SRH and disentangle the relative influence of health-related dimensions, this study aimed to empirically derive core components from a wide range of health and lifestyle variables and examine their associations with SRH in community-dwelling older adults in Japan. Methods This population-based cross-sectional study used secondary data from the 2017 Survey on Health and Life of Older Adults in Ayase City, Japan, including 1,821 community-dwelling adults aged 65 years or older. Fifty-eight items covering physical, psychological, and social domains were analyzed, incorporating standardized measures such as the Geriatric Depression Scale, Tokyo Metropolitan Institute of Gerontology Index of Competence, and the Motor Fitness Scale. Principal component analysis (PCA) was applied to identify latent components, and multiple imputation addressed missing data. Multivariable logistic regression examined associations between component scores and SRH, adjusting for age, sex, and multimorbidity. All analyses were conducted using R. Results Among the 1,821 older adults analyzed, 73.4% reported high and 26.6% reported low SRH. Participants with low SRH were older, had lower educational attainment, and were more likely to have three or more physician-diagnosed conditions (χ² = 218.87, P < 0.001). PCA identified four components explaining 49.9% of the variance: physical capability, social well-being, mobility patterns, and social participation. In multivariable logistic regression adjusted for age, sex, and number of physician-diagnosed conditions, higher physical capability was strongly associated with better SRH (odds ratio (OR) 2.63, 95% confidence interval (CI) 2.17-3.19, P < 0.001), whereas mobility patterns showed a modest negative association (OR 0.85, 95% CI 0.74-0.98, P = 0.024). Social well-being and social participation were not significantly associated with SRH. Conclusion Physical capability was the most influential determinant of SRH among community-dwelling older adults, whereas greater reliance on public transportation was modestly associated with poorer perceived health. Social well-being and social participation did not show independent associations after accounting for physical function and the number of physician-diagnosed conditions. These findings highlight the central importance of physical function and mobility independence in shaping health perception. Strategies that promote motor fitness, support independent transportation, and manage multiple conditions may enhance SRH and overall well-being in aging populations.