Developing an indicator for community-level age-friendly communities: the Japan gerontological evaluation study

Background: Age-friendly communities (AFCs) aim to create inclusive societies for older adults. The World Health Organization (WHO) highlights dementia considerations in AFC development; however, few community-level indicators include these elements. This study aimed to develop a community-level AFC indicator incorporating dementia-friendly elements based on WHO guidelines and to test its validity and reliability. Methods: A repeated cross-sectional design used data from the 2016 and 2019 waves of the Japan Gerontological Evaluation Study (JAGES) covering 61 school districts in 16 municipalities (45,162 individuals aged 65 and older in 2016 and 39,313 in 2019). The 2016 and 2019 datasets served as the development and retest samples, respectively. The item selection process involved extracting indicators from the JAGES survey items that aligned with WHO guidelines as well as those based on prior research on dementia-friendly communities (DFCs). Following expert consultations, 23 candidate items were identified. Data were aggregated at the school district level. Exploratory factor analysis (EFA) was conducted on the 2016 data to derive the factor structure, and confirmatory factor analysis (CFA) was used to assess model fit. The reproducibility of the factor structure was evaluated using EFA on the 2019 retest sample. Internal consistency and test-retest reliability were assessed. Results: The final 17-item indicator comprised three subscales: Social inclusion and dementia-friendliness (7 items, α = 0.86; e.g., Sense of belonging to the community), Social engagement and communication (5 items, α = 0.78; e.g., Participation in hobby groups), and Age-friendly physical environment (5 items, α = 0.82; e.g., Accessibility of barrier-free streets). The CFA showed an unsatisfactory model fit; however, test-retest reliability was adequate (r = 0.71–0.79; ICC = 0.67–0.78). Conclusions: A valid and reliable 17-item community-level indicator was developed, aligning with the WHO framework and incorporating dementia-friendly elements. This indicator is a valuable tool for monitoring, evaluation, and inter-community comparisons, aiding the development of AFCs and DFCs in aging societies like Japan. Additionally, this indicator can be adapted for other high-income countries with similar socioeconomic backgrounds, healthcare systems, and community structures, providing a useful tool for age- and dementia-friendly initiatives. Clinical trial number: Not applicable. © The Author(s) 2025.