Priority in interhospital transfers of patients with severe COVID-19: development and prospective validation of a triage tool

Objectives: To develop and validate a triage scale (Spanish acronym, TIHCOVID) to assign priority by predicting critical events in patients with severe COVID-19 who are candidates for interhospital transfer. Material and methods: Prospective cohort study in 2 periods for internal (February-April 2020) and external (October-December 2020) validation. We included consecutive patients with severe COVID-19 who were transported by the emergency medical service of Catalonia. A risk model was developed to predict mortality based on variables recorded on first contact between the regional emergency coordination center and the transferring hospital. The model's performance was evaluated by means of calibration and discrimination, and the results for the first and second periods were compared. Results: Nine hundred patients were included, 450 in each period. In-hospital mortality was 33.8%. The 7 predictors included in the final model were age, comorbidity, need for prone positioning, renal insufficiency, use of high-flow nasal oxygen prior to mechanical ventilation, and a ratio of PaO2 to inspired oxygen fraction of less than 50. The performance of the model was good (Brier score, 0.172), and calibration and discrimination were consistent. We found no significant differences between the internal and external validation steps with respect to either the calibration slopes (0.92 [95% CI, 0.91-0.93] vs 1.12 [95% CI, 0.6-1.17], respectively; P = .150) or discrimination (area under the curve, 0.81 [95% CI, 0.75-0.84] vs 0.85 [95% CI, 0.81-0.89]; P = .121). Conclusion: The TIHCOVID tool may be useful for triage when assigning priority for patients with severe COVID-19 who require transfer between hospitals.