Evidence-Based Adherence Classes for Combination Antihypertensive, Lipid-Lowering, and Antidiabetic Therapy

Objectives: Despite the high prevalence of multiple chronic conditions, few studies have examined adherence among patients with complex medication regimens. This study's objective was to compare differences in the patterns of adherence and subsequent outcomes among patients taking lipid-lowering, antihypertensive, and antidiabetes medications across a multi-year interval. Study Design: Retrospective observational study using administrative data from a large health plan in Hawaii. Methods: By design, the study selected members of the largest insurer in Hawaii who had prescriptions filled for all 3 types of medications from 2007 to 2010 and who had annual low-density lipoprotein and glycated hemoglobin measurements. Analyses using latent class and latent transition models identified classes of patients differing in medication adherence and determined what proportion changed classes from year to year. Analyses also compared classes in the rates of hospitalization and emergency department (ED) visits, and in the levels of serum markers. Results: The evidence-based approach identified 3 classes of patients differing in their overall adherence to the 3 study medications. Patients achieving excellent adherence had the best serum profiles and fewest ED visits and hospitalizations. About half achieved excellent adherence and possessed prescriptions more than 90% of the days. Adherence for the intermediate class ranged from 71% to 85% of the days. The least adherent group possessed filled prescriptions for the 3 medications 44% to 57% of the days. From 5% to 33% of patients transitioned among classes in adjacent years; however, patients rarely transitioned between low and excellent adherence. Conclusions: Improving from low or intermediate to excellent overall adherence can improve serum levels and lower the rates of adverse events.