Association Between Adherence to Oral Antidiabetic Medications and Cost Sharing Among Patients with Type II Diabetes: A Cross-Sectional Study.

Background: One of the critical factors that affect medication adherence is cost-sharing (the percentage that a patient pays out-of-pocket to cover health expenses), which sometimes may become a barrier to initiate or refill prescription medications.

Aim: The primary aim of this study was to assess the association between adherence to oral antidiabetic medications (OADs) using the Adherence to Refills and Medicines Scale for Diabetes (ARMS-D) questionnaire and cost-sharing among patients with type 2 diabetes. The secondary aim was to evaluate the extent to which patients are adherent to their OADs, and which factors were significantly affecting patients' adherence to their OADs.

Methods: Four hundred adult patients that visited the Diabetes Clinic of the Jordan University Hospital who were on OADs were interviewed by the researcher and were asked to complete the study questionnaire. The questionnaire consists of two sections: patients' characteristics and ARMS-D. Simple and multivariable linear regression analyses were used to assess the determinants (demographic, clinical, and economic characteristics) associated with patient's adherence to their OADs.

Results: When measured by ARMS-D (sores range from 11 to 44), where higher scores indicate lower adherence, 71% of participants reported lower adherence (scores > 11) to their OADs, while 29% achieved full adherence (scores = 11). Our analysis identified that there was no significant association between adherence to OADs and cost-sharing (P > 0.05). However, multiple regression analysis revealed that demographic factors, such as age and education level, along with clinical factors, such as the number of pills per day, the number of anti-diabetic-medications side effects, and frequent episodes of hyperglycemia, were significantly affecting patients' adherence to OADs (P < 0.05).

Conclusion: The key findings of this study indicate that the effect of patients' characteristics on adherence is therefore caused primarily by demographic and clinical factors rather than economic factors.