Adherence to medication therapy is an important factor in improving a patient’s health and assuring positive outcomes. A systematic review of barriers to adherence identified cognitive function, disease state knowledge, health literacy, polypharmacy, and patient-provider relationships as common causes of decreased medication adherence in older patients.1 Another review concluded that pharmacists’ interventions play a critical role in identifying and addressing some of the barriers of patient compliance.2 Diabetes is associated with increased mortality compared to individuals without diabetes, and medications play a key role in modifying risk factors to improve a diabetic’s morbidity and mortality.3 When prescribed medications for diabetic risk factors, approximately one-half of patients stop therapy within 12 months.3 However, a relationship between adherence, to medications and/or physician visits, and the affect on mortality in a Type 2 diabetic is not established.3
Currie and colleagues reviewed data from a longitudinal research database, The Health Improvement Network (THIN), which incorporates over 350 United Kingdom (UK) primary care practice sites to examine the relationship between compliance with physician visits and medication and mortality in Type 2 diabetics. Investigators included patients with documented type 2 diabetes treated with insulin and on at least one oral diabetic therapy or two diabetic therapies from different classes. Patients were excluded if diagnosed <35 years and started on insulin without the presence of oral antidiabetic agents or if presented with secondary diabetes. Prior to the index date for the evaluation, included patients had at least 36-months of care, including a 6-month observation period prior to starting insulin with a minimum of 30-months on insulin. The index date was established after the 36-month treatment period between January 2000 and November 2009, and mortality was assessed until death or data censorship. Noncompliance was defined as missing >1 scheduled visit or having at least one provider code for not taking a prescription medication (included all medications, not only diabetic therapies). Patients with missing data were excluded from the survival analysis.3
A total of 15,984 patients were analyzed with a 3.16-year median observation period. Medication noncompliance was found in 4.4% of diabetics and 39% of diabetics missed at least one appointment. Patients with at least one missed appointment were more likely to be smokers, younger, have a higher BMI, A1C, prior primary care contacts and morbidities. Medication noncompliance was higher in women, smokers, in patients with a higher BMI, A1C, prior primary care contacts and morbidities. Appointment nonattendance was higher in patients who were also medication noncompliant (OR 2.45, 95% CI 2.099 - 2.857). When adjusted for confounding factors, all-cause mortality was significantly higher in patients with medication noncompliance (HR 1.58, 95% CI 1.17-2.14), and clinic nonattendance (HR 1.16, 95% CI 1.04-1.30 with 1-2 missed appointments and HR 1.61, 95% CI 1.36-1.90 with > 2 missed appointments). However in diabetics who were compliant with medications, mortality increased as clinic nonattendance increased, whereas in diabetics with medication noncompliance, there was no difference in mortality as nonattendance to appointments increased.3
Overall, both medication noncompliance and clinic nonattendance were associated with increased all-cause mortality in type 2 diabetics on insulin therapy. While numerous comorbid disease states correlated with increased all-cause mortality, the study design did not allow for a cause-effect relationship to be shown or to determine if the increase in mortality was related to a worsening of glycemic or other risk factor control due to medication or clinic visit noncompliance. The rate of noncompliance with medications may ...