Exposure to guideline-recommended drugs after a first acute myocardial infarction in older adults: does deprivation matter?

Background: Inequities between guideline-recommended drugs (GRD) exposure and socioeconomic status might exist. The objective was to assess the association between a material and a social deprivation index and GRD exposure following a first acute myocardial infarction (AMI) in older adults in the province of Quebec. Methods: We conducted a retrospective cohort study using the Quebec Integrated Chronic Disease Surveillance System. Elderly ≥66 years, hospitalized for a first AMI between January 1, 2006, and December 31, 2011 and covered by the public drug plan were identified. Exposure to GRD (i.e. simultaneous use of 1) antiplatelet, 2) beta-blocker, 3) lipid-lowering and 4) angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker drugs) was assessed 30 and 365 days following hospital discharge. Associations between deprivation index and GRD exposure were estimated with log-binomial regressions adjusting for potential confounders. Results: Exposure to GRD was 52.2% and 48.0%, 30 and 365 days after hospital discharge, respectively. No statistically significant association was observed in multivariate analysis for both time points. Thirty days post hospital discharge, adjusted prevalence ratio of non-exposure to GRD was 0.98 (95% confidence interval [CI]: 0.95-1.02) for most materially deprived vs. least deprived and 1.04 (95% CI: 0.99-1.08) for most socially deprived vs. least deprived. Similar results were observed for 365 days. Conclusion: Exposure to GRD after a first urgent AMI among older adults insured by the public drug plan in the province of Quebec is relatively low. Reasons and risk groups for this low exposure should be studied to improve secondary prevention. However, results suggest equitable access to GRD, regardless of deprivation.