Accuracy of emergency medical service telephone triage of need for an ambulance response in suspected COVID-19: An observational cohort study

Background Emergency Medical Services (EMS) have experienced surges in demand as the COVID-19 pandemic has progressed with ambulances services in the UK declaring major incidents due to the risk of care being compromised. COVID-19 specific EMS telephone triage tools have been introduced to help manage demand. There has been no previous evaluation of the accuracy of EMS telephone triage in identifying patients with suspected COVID-19 at risk of serious adverse outcome. We aimed to assess accuracy of EMS telephone triage in identifying patients who need an EMS response and identify factors which affect triage accuracy. Method Patients who made an emergency call to Yorkshire Ambulance Service between 2nd April and 29th June 2020 and were assessed using an AMPDS pandemic pathway for suspected COVID-19 were linked to Office for National Statistics death registration data, hospital and general practice electronic health care data collected by NHS Digital. Accuracy of decision to dispatch an ambulance was assessed in terms of death or need for organ support at 30 days from the first 999 call. Multivariable logistic regression was used to identify factors associated with false negative and false positive triage. Results Of 12, 653 callers included in the study population, 11.1% experienced the primary composite adverse outcome. Using the triage pathway, 16% of callers did not receive an emergency response and they had a lower risk (3.5%) of the primary outcome. Ambulances were dispatched to 4, 230 callers (33.4%) who were not subsequently conveyed to hospital and did not experience the primary outcome (false positive triage). Multivariable modelling found older age and presence of pre-existing respiratory disease were significant predictors of false positive triage. Conclusion EMS telephone triage avoided 16% of calls receiving an emergency ambulance, of whom 3.5% died or needed organ support by 30 days. Telephone triage can therefore reduce the burden of EMS responses but with the cost of a small proportion of patients who do not receive an initial emergency response deteriorating. Research is needed to identify the appropriate balance between over- and under-triage