Effect of Optimised Single Role Versus Multirole Physician Response Model on Time to Contact in Patients Requiring Advanced Interventions in Greater Sydney, Australia.

Objective: This study aimed to compare the timeliness of single role versus multirole physician-staffed prehospital models and construct an optimised capability-based case allocation map for Sydney, Australia.

Methods: We retrospectively compared response, scene, and total prehospital intervals over an 11-year period. Generalized linear regression models with log function were used to control for confounders. An optimized case allocation map was derived from response time data.

Results: For the single role service 672 helicopter responses were compared with 289 road and 208 helicopter multirole responses. Multirole patients were typically closer to their base (median 18.2 km vs. 23.4 km, p = 0.004). Response interval was shorter for the single role service (median 18 min vs. 24 min, p < 0.001). Scene and total prehospital intervals were shorter for the single role service (24 min vs. 32 min, p < 0.001 and 70 min vs. 80 min, p < 0.001, respectively). On multivariate analysis, multirole allocation was significantly associated with longer scene intervals (IRR = 1.176, [95% CI 1.133, 1.221], p < 0.001) and longer total prehospital intervals (IRR = 1.402 [95% CI 1.315, 1.495], p < 0.001). The optimised case allocation map indicates multirole road response is faster for a 9 km radius circle eccentrically centred on their base. All other locations are more rapidly served by the single role helicopter model.

Conclusions: A single role model is associated with a shorter response, scene, and total prehospital intervals compared with a multirole model. Real-world response time data rather than distance can be used to optimise case allocation when response capabilities are not equivalent.