Objectives: CMS recently added medication adherence to antihypertensives, antihyperlipidemics, and oral antihyperglycemics to its Medicare Star quality measures. These CMS metrics exclude patients with <2 medication fills (ie, "early nonadherence") and patients concurrently taking insulin. This study examined the proportion of patients with diabetes prescribed cardiovascular disease (CVD) medications excluded from Star adherence metrics and assessed the relationship of both Star-defined adherence and exclusion from Star metrics with CVD risk factor control.
Study design: Cross-sectional, population-based analysis of 129,040 patients with diabetes aged ≥65 years in 2010 from 3 Kaiser Permanente regions.
Methods: We estimated adjusted risk ratios to assess the relationship between achieving Star adherence and being excluded from Star adherence metrics, with CVD risk factor control (glycated hemoglobin [A1C]<8.0%, low-density lipoprotein cholesterol [LDL-C]<100 mg/dL, and systolic blood pressure [SBP]<130 mm Hg) in patients with diabetes.
Results: Star metrics excluded 27% of patients with diabetes prescribed oral medications. Star-defined nonadherence was negatively associated with CVD risk factor control (risk ratio [RR], 0.95, 0.84, 0.96 for A1C, LDL-C, and SBP control, respectively; P<.001). Exclusion from Star metrics due to early nonadherence was also strongly associated with poor control (RR, 0.83, 0.56, 0.87 for A1C, LDL-C, and SBP control, respectively; P<.001). Exclusion for insulin use was negatively associated with A1C control (RR, 0.78; P<.0001).
Conclusions: Medicare Star adherence measures underestimate the prevalence of medication nonadherence in diabetes and exclude patients at high risk for poor CVD outcomes. Up to 3 million elderly patients with diabetes may be excluded from these measures nationally. Quality measures designed to encourage effective medication use should focus on all patients treated for CVD risk.