Measurement properties of the interest in health scale among community-dwelling older adults in Japan: Verification of the 12-item, 6-item, and 4-item versions of the interest in health scale

Objective No validated scale currently evaluates “interest in health” among older adults. This cross-sectional study assessed the structural validity, internal consistency, and construct validity of the 12-item, 6-item, and 4-item Interest in Health Scale (IHS) in community-dwelling older adults. Methods A mail survey was conducted in 2024 with 7203 independent older adults in Tsuru City, Japan. Structural validity was examined using exploratory and confirmatory factor analyses. Construct validity was assessed by analyzing the associations between IHS scores and health outcomes. Internal consistency was evaluated using Cronbach's α. Results Confirmatory factor analysis supported the original three-factor structure of the 12-item IHS (comparative fit index = 0.965), which showed good internal consistency (α = 0.80). Shortened versions strongly correlated with the original version ( r ≥ 0.85). Lower IHS scores were significantly associated with adverse health behaviors and outcomes, including physical inactivity and higher frailty risk ( p < 0.01). Conclusions The 12-item IHS is a valid and reliable measure for older adults, and its shortened versions may serve as practical screening tools by reducing response burden while maintaining psychometric integrity. The choice depends on balancing brevity for rapid screening with the need for a comprehensive understanding of health values to tailor individual interventions.