Abstract P163: Disparities By Patient Sex? Treatment Duration and Outcomes Of P2Y 12 Inhibitor Therapy in Women Compared to Men After an Acute Myocardial Infarction Among Medicare Beneficiaries

Abstract

Introduction: P2Y 12 inhibitors prevent ischemic events while increasing bleeding risk. It is unclear if clinical differences by sex justify different therapy durations after myocardial infarction (MI). Hypothesis: Women will discontinue P2Y 12 inhibitor therapy earlier than men after MI. Methods: MI hospitalizations in 2008-2013 were identified in a 20% Medicare administrative claims sample. Patients were ≥66 years old; had no recent P2Y 12 inhibitor indication; and had a P2Y 12 inhibitor prescription fill within 30 days post-MI. Therapy duration was measured using days supply and 30-day drug-free interval; duration was modeled as risk of discontinuation over time. Patients were followed up to 24 months. Adjusting for sociodemographics, clinical risks, prescriber characteristics, and contextual factors, disease risk scores (DRSs) were estimated from 4 hazard models predicting P2Y 12 inhibitor discontinuation and 3 competing risks: 1) death or hospice admission, 2) ischemic event (MI, ischemic stroke, revascularization), and 3) bleeding event. Male and female patients were matched 1:1 on the 4 DRSs using Mahalanobis distance. Cause-specific risk differences (RDs) were estimated with the Aalen-Johansen estimator and bootstrapped confidence intervals (CIs). Results: Median time on P2Y 12 inhibitor was 388 days (interquartile range 133-720). Of 30,613 patients (51.2% female), 20,002 were matched. At 24 months, women compared to men had a similar risk of treatment discontinuation (RD 0.84%; 95% CI -0.52, 2.19). While still on a P2Y 12 inhibitor, women were less likely to experience death/hospice admission (RD -0.82%; 95% CI -1.39, -0.24) or ischemic event (RD -0.92%; 95% CI -1.81, 0.06) at 24 months but had a similar bleeding risk (RD -0.07%; 95% CI -0.52, 0.39). Conclusions: Duration of P2Y 12 inhibitor use was similar in men and women. Risks for death/hospice admission and ischemic events while taking a P2Y 12 inhibitor were lower in women, suggesting a differential response to therapy that should be investigated further.