Evidence-practice gaps in P2Y12 inhibitor use after hospitalisation for acute myocardial infarction: findings from a new population-level data linkage in Australia

Background P2Y(12) inhibitor therapy is recommended for 12 months in patients hospitalised for acute myocardial infarction (AMI) unless the bleeding risk is high. Aims To describe real-world use of P2Y(12) inhibitor therapy following AMI hospitalisation. Methods We used population-level linked hospital data to identify all patients discharged from a public hospital with a primary diagnosis of AMI between July 2011 and June 2013 in New South Wales and Victoria, Australia. We used dispensing claims to examine dispensing of a P2Y(12) inhibitor (clopidogrel, prasugrel or ticagrelor) within 30 days of discharge and multilevel models to identify predictors of post-discharge dispensing and persistence of therapy to 1 year. Results We identified 31 848 patients hospitalised for AMI, of whom 56.8% were dispensed a P2Y(12) inhibitor within 30 days of discharge. The proportion of patients with post-discharge dispensing varied between hospitals (interquartile range: 25.0-56.5%), and significant between-hospital variation remained after adjusting for patient characteristics. Patient factors associated with the lowest likelihood of post-discharge dispensing were: having undergone coronary artery bypass grafting (odds ratio (OR): 0.17; 95% confidence intervals (CI): 0.15-0.20); having oral anticoagulants dispensed 180 days before or 30 days after discharge (OR: 0.39, 95% CI: 0.35-0.44); major bleeding (OR: 0.68, 95% CI: 0.61-0.76); or being aged >= 85 years (OR: 0.68, 95% CI: 0.62-0.75). A total of 26.8% of patients who were dispensed a P2Y(12) inhibitor post-discharge discontinued therapy within 1 year. Conclusion Post-hospitalisation use of P2Y(12) inhibitor therapy in AMI patients is low and varies substantially by hospital of discharge. Our findings suggest strategies addressing both health system (hospital and physician) and patient factors are needed to close this evidence-practice gap.