Psychometric validation of a culturally adapted medication literacy questionnaire in Indonesian communities: evidence from EFA and Rasch modeling

Introduction : Medication literacy describes a crucial determinant of patient safety and rational medicine use, influencing an individual’s ability to interpret instructions, avoid errors, and adhere to treatment. In Indonesia, where self-medication practices are widespread and health literacy remains uneven, no validated instrument exists to assess medication literacy. The objective of this study was to evaluate the validity and reliability of a newly developed Indonesian Medication Literacy Questionnaire using Exploratory Factor Analysis (EFA) and Rasch model approaches. Methods : A cross-sectional survey was conducted among 289 community respondents in Riau Province. The questionnaire was developed through expert panel review and pilot testing, yielding 30 initial items across four domains. Psychometric evaluation involved two stages: (1) EFA to determine factor structure, supported by the Kaiser–Meyer–Olkin measure and Bartlett’s test, factor loadings, Average Variance Extracted (AVE), and Cronbach’s alpha for reliability; (2) Rasch analysis to assess item fit, person and item reliability, separation indices, and Wright map distributions. Ethical approval was obtained from the institutional review board. Results : EFA retained 17 items forming four factors, supported by high sampling adequacy (KMO = 0.948; Bartlett’s χ² = 6013.7, p < 0.001). All factors demonstrated satisfactory convergent validity (AVE > 0.50) and internal consistency (Cronbach’s α > 0.80). Rasch analysis confirmed robust measurement properties, with item reliability = 0.97, person reliability = 0.90, and separation indices exceeding 3. Item difficulty distribution was balanced, supporting discriminatory power across respondent ability levels. Conclusion : The Indonesian Medication Literacy Questionnaire demonstrated strong validity and reliability. This culturally adapted tool can be applied in research, education, and public health interventions to improve medication safety in Indonesia.