Purpose: As medication non-adherence may exacerbate disease progression and result in drug-related problems, it is of great importance to examine the factors affecting patient’s medication adherence to develop effective solutions that help improve the communication between physicians and patients.
Methods: A questionnaire was designed based on two theories of behavior change: the theory of planned behavior (TPB) and the health belief model (HBM). The validated questionnaire was administered to patients of a regional hospital in Taipei. Item analysis included missing rate, comparisons of extreme groups, correlation between item and total score, Cronbach’s α after item deletion, and Cronbach’s α reliability test. Pearson’s correlation, multiple hierarchical regression analysis and the power of TPB and HBM models were conducted for further statistical analysis.
Results: A total of 307 valid questionnaires were analyzed. The TPB model indicated that attitude and behavioral intention exerted significant effects on medication adherence. Adjusted R-squared was 24.1%. As to the HBM model, perceived barrier and self-efficacy were significant factors. Adjusted R-squared was 28.4%.
Conclusion: The study identified several behavioral factors or barriers which might potentially affect medication adherence. Both TPB and HBM can be used to study medication adherence with the latter reporting a greater power in predicting medication adherence of chronic patients.