Use of troponin assay 99th percentile as the decision level for myocardial infarction diagnosis

Abstract

Background The Universal Definition of Myocardial Infarction recommends the 99th percentile concentration of cardiac troponin in a normal reference population as part of the decision threshold to diagnose type 1 spontaneous myocardial infarction. Adoption of this recommendation in contemporary worldwide practice is not well known. Methods We performed a cohort study of 276 hospital laboratories in 31 countries participating in the National Heart, Lung, and Blood Institute sponsored International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial. Each hospital laboratory’s troponin assay manufacturer and model, the recommended assay’s 99th percentile upper reference limit (URL) from the manufacturer’s package insert, and the troponin concentration used locally as the decision level to diagnose myocardial infarction was ascertained. Results Twenty-one unique troponin assays from 9 manufacturers were used by the surveyed hospital laboratories. The ratio of the troponin concentration used locally to diagnose myocardial infarction to the assay manufacturer-determined 99th percentile URL was <1 at 19 (6.6%) laboratories, equal to 1 at 91 (31.6%) laboratories, >1 to ≤5 at 101 (35.1%) laboratories, >5 to ≤10 at 34 (11.8%) laboratories and >10 at 43 (14.9%) laboratories. The variability in troponin decision level for myocardial infarction relative to the assay 99th percentile URL was present for laboratories in and outside of the United States, as well as for high- and standard-sensitivity assays. Conclusions There is substantial hospital level variation in the troponin threshold used to diagnose myocardial infarction; only one-third of hospital laboratories currently follow the Universal Definition of Myocardial Infarction consensus recommendation for use of troponin concentration at the 99th percentile of a normal reference population as the decision level to diagnose myocardial infarction. This variability across laboratories has important implications both for the diagnosis of myocardial infarction in clinical practice as well as adjudication of myocardial infarction in clinical trials.

High-sensitivity troponin in the evaluation of patients with suspected acute coronary syndrome: a stepped-wedge, cluster-randomised controlled trial

“…The use of high-sensitivity cardiac troponin assays and lowering the diagnostic threshold to the 99th centile remains a contentious issue in clinical practice; 5 therefore, despite guideline recommendations, 1 few institutions worldwide have adopted high-sensitivity assays. 6 , 7 If increased sensitivity does not affect the specificity of testing for the diagnosis of myocardial infarction, then introducing high-sensitivity assays will improve patient outcomes through better targeting of therapies for coronary heart disease. However, if the increase in sensitivity leads to poor specificity, then patients could be misdiagnosed, given inappropriate medications, and potentially have adverse outcomes.…”

Hip fracture care in Manitoba, Canada and New York State, United States: an analysis of administrative data

“…47 Hip fracture is an ideal condition for international comparative research because diagnosis is relatively simple and admission to hospital is standard practice in the developed world. 54 Thus, unlike with conditions such as pneumonia, joint arthroplasty or even myocardial infarction, for which patients may (or may not) seek medical care, 26,[55][56][57] patients with hip fracture tend to be comparable across geographic regions, and selection effects are minimal. 11,58 Although geographic variations in care are well described within countries, 59,60 cross-border research is much more limited.…”

Global Adoption of High-Sensitivity Cardiac Troponins and the Universal Definition of Myocardial Infarction

“…This has been demonstrated across the 276 hospital laboratories contributing to the ISCHEMIA trial, where 1 in 4 sites reported decision thresholds more than 5-fold greater than manufacturer recommendations, with the majority using contemporary cardiac troponin assays. 13 It is clear that variation also exists in the adoption of sex-specific diagnostic thresholds, despite evidence of potential benefit to reduce the under-recognition of myocardial infarction in women. 14,15 This may reflect dominance of the high-sensitivity cardiac troponin T assay which, until its U.S. approval, has not recommended sex-specific cut-off values.…”