Emergency physician estimates of the probability of acute coronary syndrome in a cohort of patients enrolled in a study of coronary computed tomographic angiography

Abstract

Introduction: Little information exists regarding how accurately emergency physicians (EPs) predict the probability of acute coronary syndrome (ACS). Our objective was to determine if EPs can accurately predict ACS in a prospectively identified cohort of emergency department (ED) patients who met enrolment criteria for a study of coronary computed tomographic angiography (CCTA) and were admitted for a ''rule out ACS'' protocol. Methods: A prospective observational pilot study in an academic medical centre was carried out. EPs caring for patients with chest pain provided whole-number estimates of the probability of ACS after clinical review. This substudy was part of the now published Rule Out Myocardial Infarction/ Ischemia Using Computer Assisted Tomography (ROMICAT) study, a study of CCTA and admission of patients for a rule out ACS protocol after a nondiagnostic evaluation. Predictions were grouped into probability groups based on the validated Goldman criteria. ACS was determined by an adjudication committee using American Heart Association/American College of Cardiology/European Society of Cardiology guidelines. Results: A total of 334 predictions were obtained for a study population with a mean age of 54 (SD 12) years, 63% of whom were male. There were 35 ACS events. EPs predicted ACS better than by chance, and increasingly higher estimates were associated with a higher incidence of ACS (p 5 0.0004). The percentage of patients with ACS was 0%, 6%, 7%, and 17%, respectively, for very low, low, intermediate, and high probability groups. EPs' estimates had a sensitivity of 63% using a . 20% probability of ACS to define a positive test. Lowering this threshold to . 7% to define a test as positive increased the sensitivity of physician estimates to 89% but lowered specificity from 65% to 24%.

Factors influencing physician risk estimates for acute cardiac events in emergency patients with suspected acute coronary syndrome

“…Overall, unstructured risk estimates were associated with overestimation of ACE risk. This finding is in line with previous research examining whether clinical gestalt is accurate for ruling out AMI 2–5. Such studies have reported moderate to high sensitivity for ruling out patients, but specificity is very low, typically around 20%–30% 3 5.…”

“…Gestalt is an appealing method of risk stratification due to its flexibility and inherent availability 2. Existing studies have shown that physician estimates of risk have moderate to high sensitivity for ruling out ACEs but tend to be conservative and overestimate risk 3–5. Such studies have dichotomised risk estimates into low-risk and high-risk when examining accuracy.…”