Triage is fundamental to emergency patient assessment. Effective triage systems accurately prioritize patients and help predict resource utilization. CTAS is a validated five-level triage score utilized in Emergency Departments (EDs) across Canada and internationally. Historically CTAS has been applied by triage nurses in EDs. Observational evidence suggests that the CTAS might be implemented reliably by paramedics in the prehospital setting. This is the first system-wide assessment of CTAS interrater reliability between paramedics and triage nurses during clinical practice.

Variables were extracted from hospital and EMS databases. EMS providers determined CTAS on-scene, CTAS pre-transport, and CTAS on-arrival at hospital for each patient (N=14,378). The hospital arrival EMS CTAS (CTAS arrival) score was compared to the initial nursing CTAS score (CTAS initial) and the final nursing CTAS score (CTAS final) incuding nursing overrides. Interrater reliability between ED CTAS initial and EMS CTAS arrival scores was assessed. Interrater reliability between ED CTAS final and EMS CTAS arrival scores, as well as proportion of patient encounters with perfect or near-perfect agreement, were evaluated.

Our primary outcome, interrater reliability [kappa=0.437 (p<0.001, 95% CI 0.421-0.452)], indicated moderate agreement. EMS CTAS arrival and ED CTAS initial scores had an exact or within one point match 84.3% of the time. The secondary interrater reliability outcome between hospital arrival EMS CTAS (CTAS arrival) score and the final ED triage CTAS score (CTAS final) showed moderate agreement with kappa =0.452 (p<0.001, 95% CI 0.437-0.466).

Interrater reliability of CTAS scoring between triage nurses and paramedics was moderate in this system-wide implementation study.