Abstract 12384: Global Variation in the Incidence of Myocardial Infarction: Increasing Nationwide Trends in Australia from 1993 to 2010

Abstract

Background: Whilst recent reports have suggested that the incidence of myocardial infarction (MI) may be declining, few have studied MI trends outside North America and Europe. We thus sought to characterize the current epidemiology of MI across the entirety of Australia.

Methods: Since 1993, the National Hospital Morbidity Dataset has included inpatient information from every hospital in Australia. Over a 17-year period from 1993 to 2010, we identified all hospitalizations with a primary diagnosis of ST-segment-elevation MI or non-ST-segment-elevation MI. We calculated incidence rates for all MIs, STEMIs and non-STEMIs per 100,000 person-years. Population estimates were sourced from the Australian Bureau of Statistics. Incidence rates were standardized to the age and sex structure of the Australian population in 2010. Time trends in the yearly number of incident MIs were assessed using negative binomial regression models, with year as a continuous predictor. Age, sex and their interaction were included in models to control for population changes over time.

Results: We identified 714,262 hospitalizations for MI between July 1993 and July 2010 (representing a period of 331,871,389 person-years). Over the study period, the age- and sex-adjusted incidence of all MIs increased from 215 to 251 cases per 100,000 person-years, a relative increase of 76% (p<0.0001 for trend). The adjusted incidence of STEMIs decreased from 147 to 70 cases per 100,000 person-years, a relative decrease of 30% (p<0.0001 for trend). In contrast, the adjusted incidence of non-STEMIs increased from 67 to 182 cases per 100,000 person-years, a relative increase of 315% (p<0.0001 for trend).

Conclusions: In contrast to previous reports, the nationwide incidence of MI has increased in recent years across Australia. These findings strengthen calls for additional, larger studies on MI incidence in diverse healthcare and sociodemographic settings outside North America and Europe.