PUBLICLY FUNDED GUIDELINE-RECOMMENDED MEDICATIONS DISPENSED TO COMMUNITY-DWELLING OLDER ADULTS IN NEW BRUNSWICK FOLLOWING HOSPITAL DISCHARGE FOR MYOCARDIAL INFARCTION BETWEEN 2009 AND 2017

Abstract

BACKGROUND: Pharmacologic therapy plays a central role in secondary prevention following myocardial infarction (MI). Evidence from randomized controlled trials has demonstrated that β-blockers, statins, renin–angiotensin–aldosterone system (RAAS) inhibitors, and antiplatelet agents, particularly P2Y12 inhibitors, reduce mortality, recurrent infarction, and stroke post-MI. Studies in Canada have shown that their use in routine practice remains variable and have not examined the determinants of medication use since P2Y12 inhibitors became standard of care. In New Brunswick (NB), population-based evidence is limited. Understanding these variations is critical for assessing the quality of post-MI care and informing system-level improvements. OBJECTIVES: This study aimed (1) to calculate the annual proportion of community-dwelling older adults (66 years or older) in NB with publicly funded drug insurance and received a dispensation for each guideline-recommended medication class: β-blockers, statins, RAAS agents, and P2Y12 inhibitors, within 90 days of discharge for MI between 2009 and 2017, and determine whether this changed over time; and (2) to determine whether characteristics of the discharging physician were associated with the likelihood of an individual receiving a P2Y12 inhibitor within 90 days of discharge. METHODS: A retrospective, population-based cohort study was conducted using linked administrative health data. The cohort included community-dwelling older adults who were discharged alive from hospital with a primary diagnosis of MI (ICD-10 I21) and had public drug coverage during the study period. Dispensation of each recommended medication within 90 days of discharge was identified from outpatient pharmacy claims. Logistic regression models with generalized estimating equations were used to estimate the associations between physician characteristics and P2Y12 inhibitor use, adjusting for patient age, sex, and length of hospital stay. RESULTS: Among the 2,674 eligible patients, the median age was 78 years (IQR: 71 to 84), and 47% were female. Overall, 79% of patients received a β-blocker, 83% a statin, 72% a RAAS inhibitor, and 70% a P2Y12 inhibitor within 90 days of discharge. Dispensation rate for β-blockers, statins, and P2Y12 inhibitors remained stable across the study period, while RAAS inhibitor use declined. Physician-level variation was evident, compared to cardiologists, patients discharged by general practitioners (OR 0.38; 95% CI 0.28, 0.51) or other specialists (OR 0.47; 95% CI 0.32, 0.68) were less likely to receive P2Y12 inhibitors post-discharge. Patients discharged by female physicians were less likely to receive P2Y12 inhibitors (OR 0.69; 95% CI 0.51, 0.92). No statistically significant associations were found with physician graduation decade or training location. DISCUSSION: Post-MI use of evidence-based pharmacotherapies among publicly insured older adults in NB was comparable to rates reported elsewhere in Canada and remained below recommended targets. The observed variation in P2Y12 inhibitor use across physician groups suggest that structural factors, such as clinical specialization, and drug reimbursement policies, may influence access to guideline-recommended therapies.