The effect of changing diagnostic algorithms on acute myocardial infarction rates

Purpose: Population rates of acute myocardial infarction (AMI) are changing. Consistent case definitions to evaluate these trends and make comparisons are essential. The World Health Organization (WHO) AMI diagnostic algorithm and clinical judgments were the standards for classification. However, in recent years, five new algorithms, to include diagnostic advances, are advocated by professional organizations. This study compares AMI rates derived from six algorithms and the impact of troponins on those rates.

Methods: The authors use the population-based Minnesota Heart Survey hospital data in 1995 and 2001 to compare six published diagnostic algorithms and the impact of troponins.

Results: In 1995 differences in AMI rates between algorithms ranged from 281/100,000 to 440/100,000 for men and 98/100,000 to 139/100,000 for women. The use of troponin, a more sensitive biomarker, adds to the differences by increasing eligible cases. Using 2001 data in patients where creatine kinase and troponin were simultaneously measured, a 64% and 95% increase in AMI rates among men and women, respectively, was observed.

Conclusions: Accurate and consistent AMI definitions are crucial for clinical trials, epidemiology and public health research. Demonstrated here is the sensitivity of AMI rates to changing case definitions and the biomarker troponin.