Age-dependent inequalities in improvements in mortality occur early after acute myocardial infarction in 478,242 patients in the Myocardial Ischaemia National Audit Project (MINAP) registry

Abstract

Background: Mortality rates after acute myocardial infarction (AMI) have declined, but there is uncertainty regarding the extent of improvements in early mortality in the elderly.

Methods: Mixed-effects regression analysis of 30-day mortality using data from 478,242 patients with AMI at 215 hospitals in England and Wales stratified by STEMI/NSTEMI, sex, and age group. A hospital opportunity-based composite score (OBCS) for aspirin, ACE-inhibitor, statin, β blocker, and referral for cardiac rehabilitation was used as measure of quality of hospital care.

Results: 30-day mortality rates (95% CI) fell from 10.7% (10.6 to 10.9%) in 2004/5 to 8.4% (8.3 to 8.6%) in 2008/9. The median (IQR) hospital OBCSs increased over time, 2004/5: 87.3 (7.2), 2006/7: 88.9 (6.3), 2008/9: 90.3 (6.1), P<0.001, and were similar between age groups (18 to <65 years, 65 to 79 years, and ≥ 80 years) for STEMI: 89.4 (6.5) vs. 89.4 (6.6), vs. 89.2 (6.5) and NSTEMI: 88.6 (7.3) vs. 88.8 (7.0) vs. 88.9 (7.0), respectively For males, all age groups except patients <65 years demonstrated a significant decrease in adjusted mortality. For females, only patients ≥ 80 years demonstrated a significant reduction in adjusted mortality. A 1% increase in hospital OBCS was associated with a 1% decrease in 30-day mortality (95% CI: 0.99 to 0.99, P<0.001).

Conclusion: In England and Wales, for patients with AMI there are age and sex-dependent differences in improvements in 30-day mortality. Whereas young males with AMI have reached an acceptable performance plateau, all other groups are either improving or, more importantly, are yet to demonstrate this.

Keywords: 30-day mortality; Acute myocardial infarction; Age; MINAP; Opportunity-base composite score; Sex.