Impact of Co-Payment Discounts on Antidepressant Medication Adherence and Costs

Objectives: In October 2009, a US health plan began a "Refill and Save Program" (RSP) with co-payment discounts for desvenlafaxine (DES) and branded extended-release venlafaxine (VENXR) when refilled within 30 days after the end of a previous antidepressant fill. This study evaluated the impact of the RSP on DES and VENXR adherence, discontinuation, and healthcare costs, versus those without the RSP benefit. Study Design: Retrospective administrative claims study. Methods: Adult commercial health plan members with >= 1 pharmacy claim for DES or VENXR (index antidepressant) from October 2009 to March 2010 were identified from a US health insurance plan. Continuous enrollment for 6 months pre-index and 9 months post index was required. Outcomes were index antidepressant proportion of days covered (PDC; days supply+follow-up days), discontinuation (>= 30-day gap), and total healthcare costs; impacts of the RSP on outcomes were modeled with ordinary least-squares, Cox proportional hazards, and log-gamma regression, respectively. Models were adjusted for index antidepressant, baseline antidepressant use, health plan characteristics, and demographics. Results: The study population (N = 46,138: 63% in RSP cohort, 37% in non-RSP cohort) had mean age 48 +/- 12 years and was 75% female. Regression-adjusted PDC was 6.3 percentage points higher (95% CI, 5.7-6.9), likelihood of discontinuation was 23.2% lower (95% CI, 0.746-0.790), and total healthcare costs were 7.6% lower (95% CI, 0.886-0.962) in the RSP cohort versus the non-RSP cohort. Conclusions: The RSP cohort had higher mean PDC, lower likelihood of discontinuation, and lower mean total healthcare costs versus the non-RSP cohort. The RSP may help improve adherence and achieve depression treatment goals.