Development and validation of the chemotherapy adherence assessment scale (CAAS)

Background Adherence to chemotherapy regimens is crucial for achieving optimal treatment outcomes in cancer patients. However, measuring adherence remains a significant challenge. This study aimed to develop and validate a comprehensive self-report tool for assessing chemotherapy adherence. Methods The Chemotherapy Adherence Assessment Scale (CAAS) was developed through a multi-stage process involving literature review, expert input, and pilot testing. Face validation was conducted with 23 subject experts, and content validity was assessed using the Content Validity Index (CVI). The CAAS was pilot-tested on 28 cancer patients undergoing chemotherapy. Psychometric properties were evaluated through internal consistency analysis (Cronbach's alpha) and Exploratory Factor Analysis (EFA). Results Face validation revealed 85% agreement among experts regarding grammar, clarity, and content. The CVI was 0.81 for individual items and 0.83 for the overall scale, indicating good content validity. Cronbach's alpha was 0.789, demonstrating strong internal consistency. The EFA yielded a robust five-factor structure, explaining 94.63% of the total variance. Most items exhibited strong factor loadings (>0.7) and high communalities (>0.7), supporting the construct validity of the CAAS. Conclusions The CAAS demonstrated robust psychometric properties, including good content validity, high internal consistency, and a well-defined factor structure capturing key dimensions of chemotherapy adherence. The CAAS represents a valuable contribution to adherence assessment in oncology settings, with potential applications in clinical practice and adherence interventions.