Factors Associated with First-Fill Adherence Rates for Diabetic Medications

A Cohort Study

Finding means of improving patients’ adherence to treatments is a critical aspect of improving outcomes. Prescriptions for drugs make up a large percentage of treatments in the United States. However, most studies on patient nonadherence to pharmaceutical regimens use refill data to understand how many patients fail to stay on medication they have used at least once. This retrospective cohort study assessed the proportion of patients who filled their initial prescriptions for a diabetes medication. The study examined data from 1,132 adults who were treated at the Geisenger Clinic, in Danville, Pa., and were prescribed a diabetes medication between 2002 and 2006.

Key Findings

  • The first-fill rate among patients prescribed a new medication for diabetes was 85 percent.
  • Analyses showed that the following variables were significantly associated with first-fill rate: higher baseline A1c (A1c is a measure of glycemic control), amount of co-pay, and choice of initial medication.
  • Some variables shown in previous studies to be associated with fill rates (age, sex, morbidity score, number of office visits, prescribing a drug during an office visit, and total number of medications ordered 10 days either before or after the index medication order) were not associated with fill rate in this study.

Although this study cannot assign causality to these associations, the authors suggest some possible explanations for their findings. For example, patients with higher baseline A1cs may receive more intensive counseling and treatment from their physicians, because their diabetes is perceived to be more advanced. In addition, patients might be more attentive to their conditions when told that their glycemic control is suboptimal. The authors note that, if their results are generalizable over larger populations, more than 200,000 diabetic patients may not be filling their initial prescriptions for an antihyperglycemic medication, thereby worsening their health outcomes and/or potentially being exposed to costly second-line drugs with more adverse effects. Future research raising awareness about prescription nonfill rates, and identification of factors related to patient failure to fill prescriptions, can help physicians improve patient acceptance, adherence to treatments, and thus improve outcomes.