Development of a questionnaire to assess the medication literacy of patients receiving oral anticancer drugs

Abstract Medication literacy is particularly important for patients undergoing oral anticancer therapy, as this treatment involves additional challenges and responsibilities compared to intravenous chemotherapy. The aim of this study was to develop a questionnaire to measure the medication literacy of patients receiving oral anticancer therapy. Following semi-structured interviews and an expert focus group, a first draft of the questionnaire was developed. The draft consisted of two parts, each containing four dimensions. Part A of the questionnaire measured patients’ self-assessed medication literacy, whereas Part B measured their functional medication literacy. After this, both parts of the draft questionnaire were evaluated by conducting a patient survey in oncology practices and community pharmacies. Based on the results of factor analyses, the questionnaire was adapted and finalised. Lastly, the criterion-related validity of the final questionnaire was tested using linear regression analysis, with the aim of investigating its possible influence on quality of life and patient enablement. Factor analysis resulted in a questionnaire that contained 27 items across 7 dimensions. A total of 307 patients was included in the patient survey. Patients achieved an average of 36.7 out of 50 points in Part A and 11.7 out of 17 points in Part B of the final instrument, with higher scores indicating better results. Part A was found to be positively associated with quality of life and patient enablement. While Part A exhibited sound psychometric criteria, Part B still lacked sufficient internal consistency. In conclusion, we developed the first medication literacy questionnaire designed completely from scratch for cancer patients receiving oral anticancer therapy. The part on self-assessed medication literacy could be used as a patient-relevant endpoint or for identifying patients in need of further support with their medication. The part on functional medication literacy needs further refinement. This project is registered in the German Clinical Trials Register (no. DRKS00034341, registration date: 2024-06-03; https://drks.de/search/en/trial/DRKS00034341 ).