Geospatial assessment of helicopter emergency medical service overtriage.

BACKGROUND Despite evidence of benefit after injury, helicopter emergency medical services (HEMS) overtriage (OT) remains high. Scene and transfer OT are distinct processes. Our objectives were to identify geographic variation in overtriage, patient-level predictors, and determine if overtriage impacts population-level outcomes. METHODS Patients ≥16 undergoing scene or interfacility HEMS in the Pennsylvania Trauma Outcomes Study were included. Overtriage was defined as discharge within 24hr of arrival. Patients were mapped to zip code and rates of OT were calculated. Hot spot analysis identified regions of high and low OT. Mixed effects logistic regression determined patient predictors of OT. High and low OT regions were compared for population-level injury fatality rates. Analyses were performed for scene and transfer patients separately. RESULTS 85,572 patients were included (37.4% transfers). OT was 5.5% among scene and 11.8% among transfer HEMS (p<0.01). Hot spot analysis demonstrated geographic variation in high and low OT for scene and transfer patients. For scene patients, OT was associated with distance (OR 1.03; 95%CI 1.01-1.06 per 10mi, p=0.04), neck injury (OR 1.27; 95%CI 1.01-1.60, p=0.04), and single-system injury (OR 1.37; 95%CI 1.15-1.64, p<0.01). For transfer patients, OT was associated with rurality (OR 1.64; 95%CI 1.22-2.21, p<0.01), facial injury (OR 1.22; 95%CI 1.03-1.44, p=0.02), and single-system injury (OR 1.35; 95%CI 1.18-2.19, p<0.01). For scene patients, high OT was associated with higher injury fatality rate (coeff 1.72; 95%CI 1.68, 1.76, p<0.01); low OT was associated with lower injury fatality rate (coeff -0.73; 95%CI -0.78, -0.68, p<0.01). For transfer patients, high OT was not associated with injury fatality rate (p=0.53); low OT was associated with lower injury fatality rate (coeff -2.87; 95%CI -4.59, -1.16, p<0.01). CONCLUSIONS Geographic OT rates vary significantly for scene and transfer HEMS and are associated with population-level outcomes. These findings can help guide targeted performance improvement initiatives to reduce HEMS overtriage. LEVEL OF EVIDENCE Epidemiological, Level IV.