Abstract
Treatment of diseases such as diabetes mellitus and cardiovascular disorders are highly dependent on medications and particularly adherence to medications to achieve optimal pharmacotherapy outcomes. Several factors can affect a patient's adherence including: knowledge and beliefs about their illness and medications, concomitant psychological disorders, type of therapeutic regimen, and lack of access to medicines. In Iran, a middle income country, essential medicines are highly available and affordable. However, adherence to medications has not been emphasized especially for patients with diabetes and cardiovascular diseases. In the present study, we reviewed the available literature on adherence to medications used to treat diabetes and cardiovascular disorders in Iran. We systematically searched Scopus, Web of Science, PubMed, CINAHL, Google Scholar, Scientific Information Database, and IranMedex using a highly sensitive protocol on July 2012. We retrieved 1003 citations; and two independent researchers screened them for relevant publications. Studies were included if they reported rate or determinants of adherence to diabetes mellitus and cardiovascular medications. Trials on improving interventions were also included. The quality of studies was assessed using appropriate guidelines. Fourteen studies were eligible for data extraction and review. The definition of adherence and the measurement tools used were unclear among studies. Methodological caveats including inappropriate sample size, sampling methods, inclusion/exclusion criteria, and high rate of loss to follow-up were also observed. Nevertheless, adherence rate was reported to be 62.8-86.3% for oral hypoglycemic medications and 38.8-60.0% for cardiovascular medicines. Forgetfulness, lack of knowledge about medical condition and prescribed medications, and concerns about medications efficacy and side effects were consistently reported as barriers to adherence. Patient education plus telephone or short message service follow-ups were reported to improve adherence to oral hypo-glycemic medications. We did not find any high quality trials on adherence to cardiovascular medicines. In conclusion, adherence to cardiovascular and diabetes medications is not assured in Iranian patients. Based on the available literature, patient education and reinforcement interventions are required to address this issue. Future studies should employ careful designs and standard tools for assessment of adherence to medications.