Warfarin Monitoring in Safety-Net Health Systems: Analysis by Race/Ethnicity and Language Preference

BACKGROUND: Racial/ethnic disparities in anticoagulation management are well established. Differences in warfarin monitoring can contribute to these disparities and should be measured. OBJECTIVE: We assessed for differences in international normalized ratio (INR) monitoring by race/ethnicity and language preference across safety-net care systems serving predominantly low-income, ethnically diverse populations. DESIGN: Cross-sectional analysis of process and safety data shared from the Safety Promotion Action Research and Knowledge Network (SPARK-Net) initiative, a consortium of five California safety-net hospital systems. PARTICIPANTS: Eligible patients were at least 18 years old, received warfarin for at least 56 days during the measurement period from July 2015 to June 2017, and had INR testing in an ambulatory care setting at a participating healthcare system. MAIN MEASURES: We conducted a scaled Poisson regression for adjusted rate ratio of having at least one INR checked per 56-day time period for which a patient had a warfarin prescription. Adjusting for age, sex, healthcare system, and insurance status/type, we assessed for racial/ethnic and language disparities in INR monitoring. KEY RESULTS: Of 8129 patients, 3615 (44%) were female; 1470 (18%), Black/African American; 3354 (41%), Hispanic/Latinx; 1210 (15%), Asian; 1643 (20%), White; and 452 (6%), other. Three thousand five hundred forty-nine (45%) were non-English preferring. We did not observe statistically significant disparities in the rate of appropriate INR monitoring by race/ethnicity or language; the primary source of variation was by healthcare network. Older age, female gender, and uninsured patients had a slightly higher rate of appropriate INR monitoring, but differences were not clinically significant. CONCLUSIONS: We did not find a race/ethnicity nor language disparity in INR monitoring; safety-net site was the main source of variation.