The relationship between depressive symptoms and oral antihyperglycemic medication adherence.

Large-scale clinical trials have demonstrated that intensive treatment with medications is one of the most important tools to achieve glycemic control in patients with diabetes. However, suboptimal adherence to anti-hyperglycemic medication has been frequently reported in the literature. The suboptimal adherence to anti-hyperglycemic medication is further aggravated by a common comorbidity of diabetes: depressive symptoms. Diabetes patients are more likely to have depression or depressive symptoms than non-diabetes patients. Furthermore, depressive symptoms may be associated with nonadherence to diabetes medications. In order to understand the relationship between depressive symptoms and medication adherence in diabetes patients, this dissertation examines how depressive symptoms are associated with patients' adherence-related beliefs and with medication adherence. A model built upon the health belief model and previous empirical studies is tested. The dissertation is a theory-based cross-sectional study using a patient self-administered questionnaire. A total of 1700 individuals with diabetes who were enrolled in a local managed care organization were invited to participate in the survey. The overall usable response rate was 47.8%. Only the 446 respondents who used only oral diabetes medications were included in the analysis. The model and hypotheses were tested by structural equation modeling. The results from structural equation modeling suggested that the effect of depressive symptoms on medication adherence was mediated through perceived non-side-effect barriers, perceived side-effect barriers, and self-efficacy. Patients with severe depressive symptoms were less confident in their ability to adhere to medication and they perceived more barriers to adherence. In turn, the reduced confidence and heightened perceived barriers had a negative impact on patients' adherence to diabetes medication regimens. The findings could benefit the development of strategies to improve the self-management of diabetes.PhDClinical psychologyHealth and Environmental SciencesPharmaceutical sciencesPsychologyPublic healthUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124375/2/3138126.pd