Diagnosis of Out-of-Hospital Cardiac Arrest by Emergency Medical Dispatchers: A Diagnostic Accuracy Study

Abstract

Introduction This study was conducted to assess the diagnostic accuracy of out-of-hospital cardiac arrest (OHCA) made by emergency medical dispatchers (EMDs) in Tehran, Iran. Methods Patients more than 18 years of age who were suspected of having an OHCA by EMDs or emergency medical service (EMS) technicians at the patient's bedside were eligible for inclusion in the study. The initial diagnosis, results of primary assessment and monitoring, and the final outcome of the mission (gold standard) were all recorded. Related archived audios were extracted from the system and listened to by the researcher (MM). Other required data were extracted from EMS mission forms and recorded in a pre-prepared checklist. After statistical analysis the accuracy was calculated. Results A total of 4732 patients were included (mean age 68.1 ± 19.7 years) of which 2830 (59.8%) were men. These cases reported by 173 EMDs that the EMDs mean age was 27.7±3.7 years, and they were all women. Cardiac arrest prevalence based on final diagnosis (gold standard) was 37.4% (95% CI: 36.0–38.8). Sensitivity and specificity of OHCA diagnosis by EMDs was 78.6% and 92.4%, respectively. Positive predictive value, negative predictive value and accuracy were 86.1% (95% CI: 84.5–87.6), 87.8% (95% CI: 86.8–88.8) and 87.3% (95% CI: 86.3–88.2), respectively. The sensitivity of diagnosis increased with increasing EMD's work experience and also increasing the number of reported OHCA cases. Conclusion Based on the results, accuracy of OHCA diagnosis by EMDs was almost 87%. It is likely that more experienced EMDs or those with more experience diagnosing OHCA are better at recognising OHCA.