Patients with AMI as an in-hospital complication were excluded. In brief, patients hospitalized between April 1, 1999, and March 31, 2001, with a ‘most responsible’ diagnosis of AMI were identified from the Canadian Institute for Health Information Discharge Abstract Database ( 8) using the International Classification of Diseases, 9th revision ( 9), code 410. The Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study ( 7) is a randomized controlled trial of the effectiveness of ‘report cards’ on indicators of quality in improving the care of patients with cardiovascular disease in Ontario. Because the components of the score (age, SBP and HR) are common predictors found in cardiovascular risk models, we aimed to test the performance of the index in both STEMI and non-STEMI patients. We sought to evaluate the utility of the TIMI risk index in the predetermined 10-point range classification used in the NRMI-3 and -4 databases for the prediction of 30-day mortality in a Canadian population-based cohort. The authors of the NRMI study suggest that the TIMI risk index could be used in the prehospital setting or at presentation as a practical tool for rapid risk stratification of patients with AMI. The discriminatory capacity of the simple TIMI risk index was good, and the proportions of observed deaths in groups based on 10-point ranges, rather than the randomized clinical trial-derived quintiles, were broadly concordant with those expected. Although the NRMI captures only in-hospital mortality and data are provided by hospitals that choose to participate, the age structure of the registry patients is more representative of the general population. Subsequently, the TIMI risk index was tested in more than 150,000 patients with STEMI from the National Registry of Myocardial Infarction (NRMI)-3 and -4 databases ( 6). The authors of the CCP study cautioned that prognostic models developed in clinical trial populations had limited value in the general population. Risk categories were based on the quintiles of the TIMI risk index from the validation study in the Intravenous nPA for Treatment of Infarcting Myocardium Early (InTIME II) trial ( 3) of fibrinolysis in patients with STEMI. Discrimination and calibration were poor among nearly 50,000 older (older than 65 years) Medicare patients on the Cooperative Cardiovascular Project (CCP) database ( 5), with deaths being underestimated in each of the five predetermined risk categories. The TIMI risk index initially failed to show that it could be generalized to the wider population. Proponents see the potential to improve outcomes, especially when a range of resources is available for an out-of-hospital diagnosis, which can lead to prehospital administration of fibrinolytics or rapid transport and access to primary percutaneous coronary intervention (PCI) ( 4). It has been advocated as a means of rapid and early triage of patients with STEMI. The TIMI risk index is based on age, heart rate (HR) and systolic blood pressure (SBP) alone, so it may be calculated at the time of first contact with the medical system. From the ‘TIMI risk score for STEMI’, a simplified ‘TIMI risk index’ was developed ( 3). The TIMI Investigators have used randomized clinical trial findings to develop risk stratification models for patients with unstable angina (UA)/non-ST-segment elevation myocardial infarction (non-STEMI) ( 1) and STEMI ( 2). Acute myocardial infarction (AMI) is associated with high early mortality, and the Thrombolysis In Myocardial Infarction (TIMI) risk index is one of the more recent models developed to identify high-risk patients. Risk stratification is part of clinical prognostication.
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