Influence of patients’ disease knowledge and beliefs about medicines on medication adherence: findings from a cross-sectional survey among patients with type 2 diabetes mellitus in Palestine

BACKGROUND: Diabetes mellitus (DM) is a common serious health problem. Medication adherence is a key determinant of therapeutic success in patients with diabetes mellitus. The purpose of this study was to assess medication adherence and its potential association with beliefs and diabetes – related knowledge in patients with type II DM. METHODS: This study was carried out at Al-Makhfia governmental diabetes primary healthcare clinic in Nablus, Palestine. Main outcome of interest in the study was medication adherence. The Beliefs about Medicines Questionnaire (BMQ) was used to assess beliefs. Morisky Medication Adherence Scale (MMSA-8(©)) was used to assess medication adherence. The Michigan diabetes knowledge test (MDKT) was used to assess diabetes – related knowledge. Univariate and multivariate analysis were carried out using Statistical Package for Social Sciences (SPSS 20). RESULTS: Four hundred and five patients were interviewed. The mean ± SD age of the participants was 58.3 ± 10.4 (range = 28 – 90) years. More than half (53.3%) of the participants were females. Approximately 42.7% of the study sample were considered non-adherent (MMAS-8(©) score of < 6). Multivariate analysis showed that the following variables were significantly associated with non-adherence: disease-related knowledge, beliefs about necessity of anti-diabetic medications, concerns about adverse consequences of anti-diabetic medications and beliefs that medicines in general are essentially harmful. Diabetic patients with high knowledge score and those with strong beliefs in the necessity of their anti-diabetic medications were less likely to be non-adherent ([O.R = 0.87, 95% CI of 0.78 – 0.97] and [O.R = 0.93, 95% of 0.88 – 0.99] respectively). However, diabetic patients with high concerns about adverse consequences of anti-diabetic medications and those with high belief that all medicines are harmful were more likely to be non-adherent ([O.R = 1.09; 95% C.I of 1.04 – 1.16] and [O.R = 1.09, 95% C.I of 1.02 – 1.16] respectively). CONCLUSIONS: Beliefs and knowledge are important factors in understanding variations in medication adherence among diabetic patients. The BMQ can be used as a tool to identify people at higher risk of non-adherence. Improving knowledge of patients about their illness might positively influence their medication adherence.