Clinical factors associated with initiation of and persistence with ADP receptor-inhibiting oral antiplatelet treatment after acute coronary syndrome: a nationwide cohort study from Finland

OBJECTIVES: To study patient selection for and persistence with ADP receptor-inhibiting oral antiplatelet (OAP) treatment after acute coronary syndrome (ACS). DESIGN: Observational, retrospective, cohort study linking real-life patient-level register data. SETTING: Nationwide drug usage study using data of patients with ACS discharged from hospitals in Finland. PARTICIPANTS: The study population consisted of 54 416 patients (aged ≥18 years) following hospital admission for unstable angina pectoris or myocardial infarction during 2009–2013. Patients were classified as either OAP or non-OAP users based on drug purchases within 7 days of discharge. OUTCOME MEASURES: Initiation of and a 12-month persistence with OAP medication. RESULTS: In total, 49% of patients with ACS received OAP treatment after hospital discharge. Women represented 40% of the population, but only 32% of them became OAP users (adjusted OR for initiation compared with men 0.8; p<0.001). Patients not treated with percutaneous coronary intervention (PCI), elderly and patients with dementia/Alzheimer's disease, atrial fibrillation or warfarin treatment were less likely to be treated with OAP. If initiated, they were less likely to complete the recommended 12 months’ medication (adjusted risk increment >38% and p<0.001 for all). The OAP users showed good compliance with immediate initiation (92% within 1 day of discharge) and high mean medication possession rate (99%). Among OAP users, the usage of other secondary prevention drugs after ACS was more common than in non-OAP-treated patients (difference >20 percentage points for each). CONCLUSIONS: Only half of the patients with ACS received guideline-recommended ADP receptor-inhibiting OAP treatment after hospital discharge, suggesting suboptimal treatment practices. Non-PCI-treated patients and patients with increased age, unstable angina, dementia or atrial fibrillation appear to have the highest risk of deficient treatment with OAPs. OAP users, however, showed good compliance during drug usage.