Reach and Validity of an Objective Medication Adherence Measure Among Safety Net Health Plan Members with Diabetes: A Cross-Sectional Study

BACKGROUND: With the expansion of Medicaid and low-cost health insurance plans among diverse patient populations, objective measures of medication adherence using pharmacy claims could advance clinical care and translational research for safety net care. However, safety net patients may experience fluctuating prescription drug coverage, affecting the performance of adherence measures. OBJECTIVE: To evaluate the performance of continuous medication gap (CMG) for diverse, low-income managed care members with diabetes. METHODS: We conducted this cross-sectional analysis using administrative and clinical data for 680 members eligible for a self-management support trial at a nonprofit, government-sponsored managed care plan. We applied CMG methodology to cardiometabolic medication claims for English- , Cantonese- , or Spanish-speaking members with diabetes. We examined inclusiveness (the proportion with calculable CMG) and selectivity (sociodemographic and medical differences from members without CMG). For val...