Statistical analysis
Myocardial Infarction, myocardial injury
MYOCARDIAL INFARCTION, DIABETES MELLITUS, MYOCARDIAL INFARCTION, REGRESSION, CEREBROVASCULAR DISEASE
The study population was stratified by the maximum cardiac troponin level on serial testing. Patients reclassified by the high sensitivity assay were defined as those with cardiac troponin I levels above the sex specific 99th centile but below the contemporary assay diagnostic threshold. Patients with high sensitivity troponin I assay levels below the sex specific 99th centile were classified as having no myocardial injury, whereas those already identified by the contemporary assay were those with any cardiac troponin I level greater than the diagnostic threshold of this assay.Using a Cox proportional hazards regression model, we compared outcomes before and after implementation of the high sensitivity assay in all patients and in those reclassified by the high sensitivity assay. The model adjusted for hospital site, season (spring, summer, autumn, with winter as the reference category), patient age, sex, comorbidities (diabetes mellitus, previous myocardial infarction, and previous cerebrovascular disease), and an indicator variable for whether the high sensitivity assay had or had not been implemented. Hospital site was fitted as a random effect, and age, sex, and comorbidities were included as fixed patient level covariates in the model. We performed a subgroup analysis stratified by the index diagnosis according to the Universal Definition of Myocardial Infarction