Medication Nonadherence in Diabetes

OBJECTIVE: To examine the longitudinal effects of medication nonadherence (MNA) on key costs and estimate potential savings from increased adherence using a novel methodology that accounts for shared correlation among cost categories. RESEARCH DESIGN AND METHODS: Veterans with type 2 diabetes (740, 195) were followed from January 2002 until death, loss to follow-up, or December 2006. A novel multivariate, generalized, linear, mixed modeling approach was used to assess the differential effect of MNA, defined as medication possession ratio (MPR) ≥0. 8 on healthcare costs. A sensitivity analysis was performed to assess potential cost savings at different MNA levels using the Consumer Price Index to adjust estimates to 2012 dollar value. RESULTS: Mean MPR for the full sample over 5 years was 0. 78, with a mean of 0. 93 for the adherent group and 0. 58 for the MNA group. In fully adjusted models, all annual cost categories increased ∼3% per year (P = 0. 001) during the 5-year study time period. MNA was associated with a 37% lower pharmacy cost, 7% lower outpatient cost, and 41% higher inpatient cost. Based on sensitivity analyses, improving adherence in the MNA group would result in annual estimated cost savings ranging from ∼661 million (MPR <0. 6 vs. ≥0. 6) to ∼1. 16 billion (MPR <1 vs. 1). Maximal incremental annual savings would occur by raising MPR from <0. 8 to ≥0. 8 (204, 530, 778) among MNA subjects. CONCLUSIONS: Aggressive strategies and policies are needed to achieve optimal medication adherence in diabetes. Such approaches may further the so-called "triple aim" of achieving better health, better quality care, and lower cost.