Validity of the Japanese version of health promoting school implementation questionnaire

Background Despite the global spread of the Health-Promoting School (HPS) framework, few validated instruments assess the depth and quality of its implementation, particularly in non-Western contexts. The Health-Promoting School Implementation Questionnaire (HPSIQ), developed in the Netherlands, has demonstrated sound psychometric properties but has not been validated in Asia. Objectives This study tested the factor structure and concurrent validity of the Japanese version of the HPS Implementation Questionnaire (J-HPSIQ) in relation to school health directors’ (SHDs’) health literacy on social determinants of health (SDH-HL). Methods A web-based survey was conducted among 1,295 staff from 174 public high and special needs schools in Japan (2023). The seven-factor structure of the 28-item J-HPSIQ—Adherence, Dose, Participant Responsiveness, Quality of Delivery, Integration, Program Differentiation, and Adaptation—was tested using confirmatory factor analysis (CFA). Convergent and discriminant validity were examined through composite reliability (CR), average variance extracted (AVE), the Fornell–Larcker criterion, and heterotrait–monotrait (HTMT) ratios. To assess concurrent validity, multiple linear regressions examined associations between SHDs’ SDH-HL and school-level implementation scores, adjusting for demographic and school-level covariates. Results The initial CFA showed moderate-to-fair fit. A subsequent structural model specified Adherence as a dependent construct predicted by Dose, Participant Responsiveness, Quality of Delivery, and Integration. This model improved fit (χ ^² (604) = 1069.62, CFI = 0.840, TLI = 0.820, RMSEA = 0.083; Δχ²(15) = 211.0, p < 0.001). All factor loadings were significant (0.34–0.87), with CR > 0.80 and AVE ≥ 0.36. SHDs’ SDH-HL was positively associated with total implementation (β = 0.21, p < 0.01), especially with Quality of Delivery (β = 0.47, p < 0.001), Integration (β = 0.23, p < 0.01), and Adaptation (β = 0.29, p < 0.01). Conclusions The J-HPSIQ is a psychometrically robust and contextually relevant tool for evaluating school health promotion in Japan. SHDs’ health literacy was positively related to effective and adaptive HPS implementation, highlighting the importance of organizational literacy for equitable and sustainable school health systems.