Impact of a Pharmacy Benefit Change on New Use of Mail Order Pharmacy among Diabetes Patients: The Diabetes Study of Northern California (DISTANCE)

Mail order pharmacies (MOPs) dispense medications by mail to the patient's home, offering convenience and eliminating access barriers (e.g., time, mobility, transportation), the benefits of which may be compounded for patients using multiple medications (Choudhry et al. 2011). Currently, one-third of all chronic disease prescriptions in the United States are dispensed by mail (Wroblewski et al. 2005). We have previously demonstrated better adherence (Duru et al. 2010), better LDL-C control (Schmittdiel et al. 2011), and no substantive safety concerns (Schmittdiel et al. 2013) among diabetic patients using MOPs. Better adherence among those using MOPs has been reported in other studies as well (Devine, Vlahiotis, and Sundar 2010; Zhang et al. 2011; Visaria, Frazee, and Devine 2012). Compared to walk-in pharmacies, MOPs can also be cost-saving for the health plan, depending on differential wastage rates between the two delivery modes, the cost of increased drug utilization, and the size of any MOP incentives (Carroll et al. 2005; Carroll 2006; Valluri et al. 2007; Devine, Vlahiotis, and Sundar 2010). The World Health Organization recommends seeking effective and low-cost, structural (system-level) approaches to improving adherence as an alternative to the frequently expensive, individual-level interventions (Sabate 2003). Financial incentives for MOPs may represent such a system-level approach if they increase the use of MOPs and secondarily improve adherence and health outcomes. However, structural changes can simultaneously improve population-level quality metrics, while also increasing social inequalities in health access and outcomes. We have previously reported lower use of MOPs among minorities and those living in deprived neighborhoods (Duru et al. 2010). While MOP use has been increasing steadily over the past two decades (Carroll et al. 2005), underuse in vulnerable groups has been observed at Kaiser Permanente Northern California (KPNC) since MOPs were introduced in 1999 (unpublished data). For example, in 2000, the prevalence of MOP use was 11 percent in Latinos, 12 percent in African Americans and Filipinos, 20 percent in Asians, and 24 percent in Caucasians. A decade later, in 2010, MOP use grew considerably, but it still lagged substantially in minorities: 37 percent in Latinos and African Americans, 46 percent in Filipinos, 63 percent in Asians, and 65 percent in Caucasians. It remains unknown whether and how financial incentives might impact disparities in MOP use (Trinacty et al. 2009). We studied a natural experiment which included a pharmacy benefit change that increased cost sharing but promoted the use of MOPs by discounting medications (i.e., reducing the increase in out-of-pocket costs) if patients prepaid two copayments and refilled using MOPs. We evaluated the following: (1) the overall effect of rolling out the benefit change on subsequent uptake of MOPs for dispensing of cardiometabolic medications among patients with diabetes, and (2) whether the rollout's effect on MOP uptake was uniform across social strata (defined by ethnicity, educational attainment, household income, English proficiency, or health literacy).