Objective: To explore the impact of the implementation of eCTAS, a real-time electronic decision-support tool, on hospital admission, rate of left without being seen, and time from triage to physician initial assessment.

Methods: We conducted a cohort study using population-based administrative data from all Ontario emergency departments (EDs) that had implemented eCTAS for 9 months. We compared 6 months post-eCTAS data to the same 6 months the previous year (pre-eCTAS). We included triage encounters of adult (≥ 18 years) patients if they had one of 16 pre-specified, high-volume presenting complaints. Multivariable logistic regression and quantile regression models informed the effect of eCTAS on outcomes.

Results: We included data from 354,176 triage encounters from 31 EDs. There was a change in the distribution of triage scores post-eCTAS, with fewer patients classified as CTAS 2 and CTAS 3, and more patients classified as CTAS 1 and CTAS 4. Overall, hospital admission decreased post-eCTAS (adjusted OR: 0.98; 95% CI: 0.97 to 1.00), with fewer CTAS 2 and more CTAS 3 and CTAS 4 patients admitted post-eCTAS. The rate of left without being seen increased (2.8% vs. 3.0%; adjusted OR: 1.07; 95% CI: 1.03 to 1.11) post-eCTAS, while time to physician initial assessment proved similar pre and post-eCTAS.

Conclusions: eCTAS implementation had little impact on admission, rate of left without being seen and time to physician initial assessment. eCTAS appears to reclassify patients from higher to lower acuity scores, resulting in higher admission rates for CTAS 3 and CTAS 4 patients. It remains unknown if this reclassification is appropriate.