External Validation of the SCARE Score for Predicting Acute Myocardial Infarction in Patients Calling Emergency Medical Communication Centers: A Prospective Multicenter Study

OBJECTIVES: Chest pain triage during emergency medical dispatch must balance early identification of acute myocardial infarction (AMI) with appropriate allocation of prehospital resources. Our objectives were to externally validate the SCARE score for discrimination of hospital-diagnosed AMI among adults hospitalized after Emergency Medical Communication Center (EMCC) calls for non-traumatic chest pain and to evaluate performance by sex. METHODS: This prospective observational multicenter study included adults hospitalized after an EMCC call for non-traumatic chest pain in four French physician-staffed EMCCs between October 2019 and February 2020. During calls, clinicians prospectively recorded standardized variables used to reconstruct the SCARE score retrospectively; the score was unavailable in real time and did not influence dispatch decisions. The primary analysis assessed the SCARE score's ability to discriminate hospital-diagnosed AMI adjudicated from hospital records according to the Fourth Universal Definition of Myocardial Infarction. Discrimination was assessed using the AUROC, with sex-stratified analyses as a secondary objective, and threshold-based test characteristics were additionally reported for the pre-specified high-risk threshold of >35 points. Calibration was explored using the Hosmer-Lemeshow test and Brier score. RESULTS: Among 2,042 analyzed patients, 265 (13.0%) had AMI. The SCARE score showed good discrimination, with an AUROC 0.85 (95% CI 0.82-0.87). Calibration appeared acceptable (Hosmer-Lemeshow p = 0.637; Brier score = 0.095). At the prespecified high-risk threshold of >35 points, sensitivity was 73.6% (95% CI 67.9-78.5), specificity 75.3% (95% CI 73.2-77.2), positive predictive value 30.8% (95% CI 27.3-34.5), and negative predictive value 95.0% (95% CI 93.7-96.0). AMI increased from 2.4% in the low-risk category to 31.0% in the high-risk category. In sex-stratified analyses, AUROC was 0.84 (95% CI 0.81-0.86) in men and 0.89 (95% CI 0.86-0.92) in women (DeLong p = 0.006). CONCLUSIONS: In this multicenter cohort of patients hospitalized with chest pain after calling a French EMCC, the SCARE score showed good discrimination for hospital-diagnosed AMI and may support prioritization of advanced prehospital resources. However, it should not be used as a stand-alone rule-out tool and does not address other life-threatening causes of chest pain. Prospective validation in all chest pain callers and in non-physician dispatch systems is needed.