OBJECTIVES: Medication fill rate after doctor’s electronic prescriptions can be a useful measure for adherence. The objective of the study was to utilize prescription data in electronic medical records (EMR) linked with pharmacy claims data to examine the prescription fill rates and factors associated with it.

METHODS: Using a large claims-EMR linked data, patients who had a prescription for either an antibiotic, antihypertensive, or antidiabetic in EMR were identified (index prescription). Prescription fill was defined as a pharmacy claim found within the 90 days following the EMR prescription. For each medication group and specific therapeutic classes within each group, characteristics of patients and fill rates were examined using descriptive statistics. Logistic regression was used to evaluate the association between fill rates and factors such as age, race, brand versus generic, and prior treatment history during the 365 days before the index prescription.

RESULTS: There were 77,996 patients with index antibiotic prescription, 78,462 with index antihypertensive prescription, and 24,013 with index antidiabetic prescription. The prescription fill rate after EMR orders was 73%, 74%, and 76 %, respectively. In general, African American race was negatively associated with fill rates (Odds ratio [OR] 0.8 for all three groups). Prior treatment history had positive effect on fill rates in patients receiving antihypertensives (OR 5.6, 95% Confidence interval 5.4-5.7) or antidiabetics (OR 4.1, 3.8-4.4) in contrast to its negative effect in patients receiving antibiotics (OR 0.6, 0.6-0.6). Older age was an additional factor that was negatively associated with the fill rate among patients without prior treatment history.

CONCLUSIONS: Significant proportions of patients, especially patients with no prior treatment history, did not fill their prescription for antibiotics, antihypertensives, or antidiabetics. The impact of factors associated with medication fill rates varied across different medication groups.