Guidelines recommend dual antiplatelet therapy (DAPT) with acetylsalicylic acid (ASA) and ticagrelor following acute coronary syndrome (ACS) regardless of management strategy. Despite this, prescription practices lag and appropriate DAPT is not utilized.
We aimed to trend differences in P2Y12 inhibitor prescriptions between ACS patients managed with percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). As well, we wanted to analyze the impact practice-changing trial publications, national guideline updates, and publicly funded drug coverage plans may have on prescription patterns.
From national databases, we obtained data for ACS patients in the province of Ontario, Canada between 2008 and 2018. Using an interrupted-time series with data aggregated monthly, we evaluated types of P2Y12 inhibitor prescribed at hospital discharge and changes to antiplatelet prescription patterns following publication of Ticagrelor versus Clopidogrel in Patients with Acute Coronary Syndrome (PLATO), Canadian Cardiovascular Society (CCS) antiplatelet therapy guidelines, and ticagrelor coverage by a publicly funded medication plan.
We included 114,142 ACS patients; 49% underwent PCI and 8% required CABG. Between October 2008 and March 2018, the proportion of patients discharged on P2Y12 inhibitors increased from 73.4% to 87% (p<0.0001) for PCI patients and 11.4% to 31.4% (p<0.0001) for CABG patients. PLATO publication was associated with a 1.3% (p=0.002) monthly decline in clopidogrel prescriptions amongst PCI patients. The 2010 CCS antiplatelet therapy guidelines were associated with a 0.7% (p<0.0001) monthly decline in clopidogrel prescriptions amongst PCI patients. The approval of ticagrelor by publicly funded medication plan was associated with an increase in ticagrelor prescriptions within the first month (24.5%; p<0.0001) and a continued monthly increase (0.4%; p<0.0001) in PCI patients. The approval was also associated with an increase in monthly ticagrelor prescriptions (0.2%; p<0.0001) amongst CABG patients. The 2012 CCS antiplatelet therapy guidelines were associated with a decline in clopidogrel prescriptions within the first month (6.1%; p=0.003) and a monthly increase in ticagrelor prescriptions (0.3%; p=0.05) amongst PCI patients.
Drug coverage by a publicly funded medication plan and guideline updates had significant impact on P2Y12 inhibitor prescription practices. Despite improvements, P2Y12 inhibitor prescriptions for CABG patients are far behind PCI patients. Further research is necessary to address barriers to appropriate antiplatelet therapy in the ACS population.
Antiplatelet Prescription Patterns
Type of funding source: Public hospital(s). Main funding source(s): New Investigator Fund - Hamilton Health Sciences Foundation, Hamilton, Canada