Dispensing channel and medication adherence: evidence across 3 therapy classes.

OBJECTIVES: To examine the association of mail order versus retail pharmacy dispensing channels with medication adherence for patients on diabetes, hypertension, or high blood cholesterol medications, controlling for prior adherence behavior (PAB) and days of supply. STUDY DESIGN: Retrospective analysis using de-identified pharmacy claims data from a large national pharmacy benefits manager between April 2009 and December 2011. METHODS: Continuously eligible patients with an antidiabetic, antihypertensive, or antihyperlipidemic prescription claim between October and December 2009 were identified and followed over a 2-year period. Multivariate logistic regression was used to evaluate the impact of dispensing channel on medication adherence, controlling for differences in demographics, disease burden, and drug use pattern. Patients with a medication possession ratio of 80% or greater were considered adherent. The analysis controlled for PAB by using patients' adherence status in 2010. RESULTS: Overall, patients using the mail order channel had higher adherence rates than their retail counterparts across all 3 therapeutic classes. In 2011, the likelihood of a mail order patient being adherent was approximately 1.15 times higher than that of a retail patient for antidiabetics, 1.11 times higher for antihypertensives, and 1.19 times higher for antihyperlipidemics. PAB was the strongest contributor to the odds of a patient being adherent across all 3 therapy classes: odds ratios ranged from 5.87 to 9.49. CONCLUSIONS: After adjusting for PAB, differential days of supply, and differences in demographics and disease burden, patients who use mail order have a greater likelihood of being adherent than patients who use a retail pharmacy.