Long term excess mortality associated with diabetes following acute myocardial infarction: A population-based cohort study

Background The long-term excess risk of death associated with diabetes following acute myocardial infarction is unknown. We determined the excess risk of death associated with diabetes among patients with ST-elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) after adjustment for co-morbidity, risk factors and cardiovascular treatments. Methods Nationwide population-based cohort (STEMI n=281,259 and NSTEMI n=422,661) using data from the UK acute myocardial infarction registry, MINAP, between 1st January, 2003 and 31st June, 2013. Age, sex, calendar year and country-specific mortality rates for the populace of England and Wales (n=56.9 million) were matched to cases of STEMI and NSTEMI. Flexible parametric survival models were used to calculate excess mortality rate ratios (EMRR) after multivariable adjustment. This study is registered at ClinicalTrials.gov (NCT02591576). Results Over 1.94 million person-years follow-up including 120,568 (18.9%) patients with diabetes, there were 200,360 (28.4%) deaths. Overall, mortality was higher among patients with than without diabetes (35.8% vs. 25.3%). After adjustment for age, sex and year of acute myocardial infarction, diabetes was associated with a 72% and 67% excess risk of death following STEMI (EMRR 1.72, 95% CI 1.66-1.79) and NSTEMI (1.67, 1.63-1.71). Diabetes remained significantly associated with substantial excess mortality despite cumulative adjustment for co-morbidity (EMRR 1.52, 95% CI 1.46-1.58 vs. 1.45, 1.42-1.49), risk factors (1.50, 1.44-1.57 vs. 1.33, 1.30-1.36) and cardiovascular treatments (1.56, 1.49-1.63 vs. 1.39, 1.36-1.43). Conclusion At index acute myocardial infarction, diabetes was common and associated with significant long-term excess mortality, over and above the effects of co-morbidities, risk factors and cardiovascular treatments.