A medication literacy instrument for older chronic disease patients in China: development and validation

Abstract Background Medication literacy is crucial for the safe and effective use of drugs among older adults with chronic conditions. However, a validated instrument tailored to older Chinese patients with multiple chronic diseases is lacking. This study aimed to develop and validate a medication literacy scale specific to this population. Methods This study utilized a cross-sectional design. We aimed to adhere to the COSMIN criteria where feasible.Items were initially derived from the Chinese Pharmaceutical Association’s Medication Behavior Risk KAP Questionnaire, then refined by an expert panel based on Nutbeam’s health literacy model and Pantuzza’s medication literacy components. A pilot survey of 114 older chronic disease patients (aged ≥ 60 years, taking ≥ 2 medications) was used to improve content validity and wording clarity. The main survey employed simple random sampling across primary, secondary, and tertiary hospitals in the Beijing–Tianjin–Hebei region. Participants completed an online self-administered questionnaire covering sociodemographics and medication literacy. Extended factor analysis (EFA) and confirmatory factor analysis (CFA) were used to evaluate construct validity. The content validity index (CVL) is used as a quantitative evaluation index of the content validity of the scale. The item level content validity index (i-cvi) and the scale level content validity index (s-cvi) are used to evaluate the content validity of the items and the scale as a whole. Results The exploratory factor analysis extracted 12 common factors with feature values > 1 and factor loadings > 0.5. The total cumulative variance contribution rate is 68.958%. After confirmatory factor analysis, the medication literacy instrument contains 41 items in nine dimensions. The total scale demonstrated excellent internal consistency (Cronbach’s α = 0.918), while all subscales exceeded the threshold of 0.7. Confirmatory factor analysis revealed that the degree of fit of the model was good (χ 2/df = 2.437, IFI = 0.913, TLI = 0.901, CFI = 0.912, and RMSEA = 0.050). We classified participants into two groups: basic medication literacy (total score ≥ 156 or an average score ≥ 3.81) and low medication literacy (total score <156 or an average score <3.81). Conclusions The newly developed medication literacy scale exhibits strong psychometric properties and is suitable for assessing medication literacy among Chinese older patients with chronic diseases. It shows promise for use in clinical and public health settings to identify at-risk individuals and guide targeted interventions.