Medication literacy scale for patients with chronic constipation in Japan

Chronic constipation (CC) is a common gastrointestinal disorder. The disease-specific medication literacy (ML) of people with CC should be assessed because appropriately managing laxatives requires professional guidance, and patients must be able to understand and manage medications. The aim in this study was to develop a Medication Literacy Scale for Patients with Chronic Constipation (MLS-PCC) and evaluate the validity in accordance with the Consensus-based Standards for the selection of health measurement instruments guidelines. The MLS-PCC was developed through item generation and qualitative pilot surveys, followed by quantitative pilot surveys to evaluate content validity. An online cross-sectional survey was then administered to 423 adults with CC in Japan. The structural validity was evaluated using exploratory and confirmatory factor analyses. Between-group differences in the total and subscale scores were examined. The final MLS-PCC comprised nine items within three factors—functional, interactive, and critical subscales. The fit of the model was good (CFI = 0.98, TLI = 0.96, and RMSEA = 0.058), with satisfactory reliability ( ω = 0.84 for the total scale). The ML scores were substantially higher for women, those with a higher education level, those with gastrointestinal comorbidities, those receiving care in specialty departments, and those taking new laxative prescriptions. The content and structural validity of the MLS-PCC were high; the MLS-PCC can serve as a practical tool for assessing ML among patients with CC. The MLS-PCC may support pharmacists and other healthcare professionals in optimizing patient education, enhancing communication, and promoting safe and effective medication use. • A medication literacy scale was developed for chronic constipation patients. • Content and structural validity were confirmed using COSMIN-based procedures. • The scale differentiates medication literacy by sex, education, and clinical factors. • The scale can guide pharmacist-led interventions for safe laxative use.