Introduction: While P2Y12 inhibitors (P2Y12i) are essential pharmacotherapy after percutaneous coronary intervention (PCI), few studies have investigated differences in P2Y12i utilization or adherence among the different P2Y12 inhibitors (i.e., clopidogrel, prasugrel, and ticagrelor) after PCI.
Methods: We used administrative claims from a large, national commercial payer (n=15 million annual covered lives) during years 2008-2014 and measured P2Y12i use following hospital discharge for primary or elective PCI among P2Y12i-naïve patients 18 to 64 years of age. Data consisted of inpatient claims with diagnosis and procedure codes as well as outpatient pharmacy claims including National Drug Codes, fill dates, quantity, and days supplied. Patients were classified based on whether they filled any P2Y12i within 30 days of PCI, and by the type of P2Y12i filled. Among patients who received a drug eluting stent (DES) and who filled P2Y12i within 30 days after PCI, medication adherence at 6 and 12 months was calculated using medication possession ratios.
Results: We identified 47,090 P2Y12i-naïve PCI patients from 2008-2014. In 2008, 93% of patients were discharged on clopidogrel and 7% did not fill any P2Y12i within 30 days. By 2014, 51% of patients were prescribed clopidogrel, 33% on prasugrel or ticagrelor, and 16% did not fill any P2Y12i within 30 days. Among n=32,840 patients who received a DES and filled a P2Y12i within 30 days, medication adherence at 6 months for patients started on clopidogrel, prasugrel, and ticagrelor was 90%, 87%, and 83% respectively (p = <.001). At 12 months, adherence to clopidogrel, prasugrel, and ticagrelor was 78%, 75%, and 69% respectively (p = <.001).
Conclusions: By 2014, one third of PCI patients filled prescriptions for either prasugrel or ticagrelor within 30 days. These newer antiplatelet agents had lower medication adherence rates at 6 months and 12 months compared to clopidogrel. Notably, the percentage of patients not filling any P2Y12i after PCI more than doubled from 2008 to 2014. Our findings suggest that both initiation and adherence to P2Y12i therapy after PCI have decreased during the time period when newer, more expensive P2Y12 inhibitors were introduced.