Refill adherence and polypharmacy among patients with type 2 diabetes in general practice

Background and Aims Non-adherence is considered a major barrier to better outcomes of diabetes care. A relationship has been established between polypharmacy and patients' adherence. This study aims to investigate the occurrence of polypharmacy and non-adherence in general practice, their mutual relationship and the association between adherence and the intermediate outcomes of diabetes care. Materials and Methods We used the baseline and follow-up data of a randomised controlled trial (RCT) that compared usual care with care in accordance with a locally adapted national guideline. This study took place in the Netherlands and involved 30 general practices and 1283 patients. We obtained a complete medication profile of all participants and calculated the number of prescribed drugs and the adherence indices (AI) for oral blood glucose, blood pressure and cholesterol lowering drugs. Patients with an adherence index = 0.8 for oral blood glucose, blood pressure and cholesterol lowering drugs. In the intervention group, increase of drug prescriptions exceeded that of controls (1.1 +/- 2.0 vs. 0.6 +/- 1.5, p <0.001, adjusted p