Association between patients’ beliefs and oral antidiabetic medication adherence in a Chinese type 2 diabetic population

PURPOSE: The objective of this study was to identify, using the theory of planned behavior (TPB), patients’ beliefs about taking oral antidiabetic drugs (OADs) as prescribed, and to measure the correlations between beliefs and medication adherence. PATIENTS AND METHODS: We performed a cross-sectional study of type 2 diabetic patients using structured questionnaires in a Chinese tertiary hospital. A total of 130 patients were enrolled to be interviewed about TPB variables (behavioral, normative, and control beliefs) relevant to medication adherence. Medication adherence was assessed using the eight-item Morisky Medication Adherence Scale (MMAS-8). Spearman’s rank correlation was used to assess the association between TPB and MMAS-8. Logistic regression analysis was performed to examine the relationship between different variables and MMAS-8, with statistical significance determined at P<0.05. RESULTS: From 130 eligible Chinese patients with an average age of 60.6 years and a male proportion of 50.8%, a nonsignificant relationship between behavioral, normative, and the most facilitating control beliefs and OAD adherence was found in our study. Having the OADs on hand (P=0.037) was the only facilitating control belief associated with adherence behavior. Being away from home or eating out (P=0.000), not accepting the disease (P=0.000), ignorance of life-long drug adherence (P=0.038), being busy (P=0.001), or poor memory (P=0.008) were control belief barriers found to be correlated with poor adherence. TPB is the only important determinant influencing OAD adherence among all the factors (P=0.011). CONCLUSION: The results indicate that the TPB model could be used to examine adherence to OADs. One facilitating control belief, and most of the barrier control beliefs of TPB were related to medication adherence among Chinese type 2 diabetes inpatients. It will be helpful to understand patients’ self-medication and provide methods to develop instruments for identifying factors that influence OAD adherence.