Impact of provincial and national implementation strategies on P2Y12 inhibitor utilization for acute coronary syndrome in the elderly: an interrupted time series analysis from 2008 to 2018.

Background: Guidelines recommend both acetylsalicylic acid and ticagrelor following acute coronary syndrome (ACS), but appropriate prescription practices lag. We analyzed the impact of government medication approval, national guideline updates, and publicly funded drug coverage plans on P2Y12 inhibitor utilization.

Methods: Accessing provincial databases, we obtained data for elderly ACS patients in Ontario, Canada, between 2008 and 2018. Using interrupted-time series with descriptive statistics and segmented regression analysis, we evaluated types of P2Y12 inhibitors prescribed at discharge and changes to their utilization in patients managed with percutaneous intervention (PCI), coronary artery bypass grafting (CABG) or medically, following national antiplatelet therapy guidelines (by the Canadian Cardiovascular Society), ticagrelor's national approval by Health Canada, and ticagrelor's coverage by a publicly funded medication plan.

Results: We included 114,142 patients (49.4%-PCI; mean age 75.71±6.94 and 62.3% male and 7.7%-CABG; mean age 74.11±5.63 and 73.5% male). Among PCI patients, clopidogrel utilization declined monthly after 2010 national guidelines were published (p<0.0001) and within the first month after ticagrelor's national approval by Health Canada (p=0.03). Among PCI patients, ticagrelor utilization increased within the first month (p<0.0001) and continued increasing monthly (p<0.0001) after its coverage by a publicly funded medication plan. Among PCI patients, clopidogrel utilization declined within the first month (p=0.003) and ticagrelor utilization increased monthly (p=0.05) after 2012 CCS guidelines. Among CABG patients, ticagrelor's coverage was associated with a monthly increase in its utilization (p<0.0001).

Conclusion: National guideline updates and drug coverage by a publicly funded medication plan significantly improved P2Y12 inhibitor utilization. Barriers to appropriate antiplatelet therapy in the surgical population must be explored.