Age-dependent improvements in survival after hospitalisation with acute myocardial infarction: an analysis of the Myocardial Ischemia National Audit Project (MINAP)

Abstract

Background: recent studies report an age-dependent decline in mortality after acute myocardial infarction (AMI).

Objective: to investigate age-dependent improvements in survival after hospitalisation with AMI.

Design: population-based cohort study using data from the Myocardial Ischaemia National Audit Project.

Subjects: a total of 583,466 patients with AMI admitted to 247 hospitals between 1 January 2003 and 31 December 2010.

Methods: six-month relative survival (RS) was calculated from the ratio of observed to expected survival using an age-, sex- and biennial year-matched population from the Office for National Statistics. Risk-adjusted mortality rates (RMAR) were estimated using shared frailty regression. Data were stratified by age group, AMI phenotype [(ST-elevation myocardial infarction, (STEMI) and non-STEMI, (NSTEMI)] and period of admission to hospital.

Results: for STEMI, there was an increase in RS for patients aged 65-80 years (84.8 versus 89.2%) and those over 80 years (68.0 versus 71.8%), but not for patients aged 18 to <65 years (96.4 versus 96.9%). For NSTEMI patients aged 18 to <65 years RS was higher, but stable (95.5 versus 96.8%) and improved for patients aged 65-80 years (83.2 versus 88.5%) and patients aged >80 years (68.3% versus 75.5%). Likewise, RMAR improved for patients aged ≥65 years, were stable and higher for patients <65 years.

Conclusions: there were significant improvements in survival after hospitalisation with AMI in the older but not younger patients. The scope for further reductions in mortality is likely to be much greater for older than younger patients with AMI.

Keywords: MINAP; acute myocardial infarction; age; older people; survival.