Adherence to Newly Prescribed Diabetes Medications Among Insured Latino and White Patients With Diabetes

Importance Medication adherence is essential to diabetes care. Patient-physician language barriers may affect medication adherence among Latino individuals. Objective To determine the association of patient race/ethnicity, preferred language, and physician language concordance with patient adherence to newly prescribed diabetes medications. Design, Setting, and Participants This observational study was conducted from January 1, 2006, to December 31, 2012, at a large integrated health care delivery system with professional interpreter services. Insured patients with type 2 diabetes, including English-speaking white, English-speaking Latino, or limited English proficiency (LEP) Latino patients with newly prescribed diabetes medication. Exposures Patient race/ethnicity, preferred language, and physician self-reported Spanish-language fluency. Main Outcomes and Measures Primary nonadherence (never dispensed), early-stage nonpersistence (dispensed only once), late-stage nonpersistence (received ≥2 dispensings, but discontinued within 24 months), and inadequate overall medication adherence (>20% time without sufficient medication supply during 24 months after initial prescription). Results Participants included 21 878 white patients, 5755 English-speaking Latino patients, and 3205 LEP Latino patients with a total of 46 131 prescriptions for new diabetes medications. Among LEP Latino patients, 50.2% (n = 1610) had a primary care physician reporting high Spanish fluency. For oral medications, early adherence varied substantially: 1032 LEP Latino patients (32.2%), 1565 English-speaking Latino patients (27.2%), and 4004 white patients (18.3%) were either primary nonadherent or early nonpersistent. Inadequate overall adherence was observed in 1929 LEP Latino patients (60.2%), 2975 English-speaking Latino patients (51.7%), and 8204 white patients (37.5%). For insulin, early-stage nonpersistence was 42.8% among LEP Latino patients (n = 1372), 34.4% among English-speaking Latino patients (n = 1980), and 28.5% among white patients (n = 6235). After adjustment for patient and physician characteristics, LEP Latino patients were more likely to be nonadherent to oral medications and insulin than English-speaking Latino patients (relative risks from 1.11 [95% CI, 1.06-1.15] to 1.17 [95% CI, 1.02-1.34]; P P P P  > .28). Conclusions and Relevance Nonadherence to newly prescribed diabetes medications is substantially greater among Latino than white patients, even among English-speaking Latino patients. Limited English proficiency Latino patients are more likely to be nonadherent than English-speaking Latino patients independent of the Spanish-language fluency of their physicians. Interventions beyond access to interpreters or patient-physician language concordance will be required to improve medication adherence among Latino patients with diabetes.