Statins After Myocardial Infarction in the Oldest: A Cohort Study in the Clinical Practice Research Datalink Database

Abstract

OBJECTIVE: To explore the effect of initiating statins for secondary prevention after a first myocardial infarction (MI) in patients aged 80 years and older. DESIGN: Retrospective cohort study. SETTING: Clinical Practice Research Datalink (1999-2016). PARTICIPANTS: Patients, aged 65 years and older, hospitalized after a first MI without a statin prescription in the year before hospitalization. The age group of 65 to 80 years was included to compare our results to current evidence. MEASUREMENTS: The primary outcome was a composite of recurrent MI, stroke, and cardiovascular mortality; and the secondary outcome was all-cause mortality. A time-varying Cox model was used to account for statin prescription over time. We compared at least 2 years of statin prescription time with untreated and less than 2 years of prescription time. Analyses were adjusted for potential confounders. The number needed to treat (NNT) was calculated based on the adjusted hazard ratios (HRs) and corrected for deaths during the first 2 years of follow-up. RESULTS: A total of 9020 patients were included. Among the 3900 patients aged 80 years and older, 2 years of statin prescriptions resulted in a lower risk of the composite outcome (adjusted HR = 0.81; 95% confidence interval [CI] = 0.66-0.99) and of all-cause mortality (adjusted HR = 0.84; 95% CI = 0.73-0.97). During 4.5 years of median follow-up, the NNT for prevention of the primary outcome was 59; and for mortality, the NNT was 36. Correcting for 36.2% deaths during the first 2 years increased the NNT on the primary outcome to 93 and to 61 on all-cause mortality. CONCLUSION: Our data support statin initiation after a first MI in patients aged 80 years and older if continued for at least 2 years. Especially in patients with a low risk of 2-year mortality, statins should be considered.