A prediction model for prehospital triage of patients with suspected cardiac ischemia

The American College of Cardiology recommends that patients with high risk acute myocardial infarction (AMI) be triaged to hospitals with percutaneous transluminal coronary angioplasty capability. However, there are no prehos pital triage criteria to select candidates for bypassing community hospital s and being taken directly to "cardiac centers." This article assesses whic h independent variables predict death within 7 days in patients with suspec ted AMI transported by EMS. This is a retrospective study of 291 AMI patien ts transported by ambulance to 3 hospitals during 1996-1997. Included were patients who were (n = 244) greater than or equal to 18 years of age, had a ED chief complaint of chest I,ain or dyspnea for whom we had mortality dat a. Mortality at 7 days, our primary outcome measure, was obtained by using a metropolitan Detroit tricounty death index records. Differences between t he survivors and nonsurvivors were assessed using the Student's t-test and chi-square tests. Multiple triage criteria were assessed for optimal identi fication of high risk patients by constructing a logistic multivariate mode l. Among the study population, 15% died within 7 days (95% confidence inter val (CI) 10.3-19.2), and this group represented 63.2% of all deaths over a 2 year surveillance period. Survivors. compared to nonsurvivors, were 14.1 years younger (P less than or equal to .001) and more often men (P less tha n or equal to 0.001). The dispatch time to ED arrival was less among surviv ors than nonsurvivors (42.8 vs. 50.6 min, P less than or equal to .01). EMS vital signs differed by survivor status. Among survivors, HR was lower (-1 1.9 bpm; P less than or equal to 0.01), RR was lower (-6.7 rpm: P less than or equal to .001), SBP was higher (+14.5 mmHg P less than or equal to 0.05 ) and DBP was higher (+13.2 mm Hg; P less than or equal to .01). A multivar iate model identified the following as independent predictors of carl) mort ality: female gender (OR = 2.3; P less than or equal to .05), age greater t han or equal to 65 (OR = 5.9; P less than or equal to .01), RR greater than or equal to 20 (OR = 4.6: P less than or equal to .001), SBP < 120 (OR = 2 .4; P <less than or equal to> .05). The overall model was 86% sensitive and 53% specific with an area under the receiving operating characteristic cur ve of 0.8 (P less than or equal to .001). A triage rule based on a multivar iate model can identify the group at high risk of early cardiac death. This decision rule needs to be prospectively validated.