Population-based analysis of the effect of a comprehensive, systematic change in an emergency medical services resource allocation plan on 24-hour mortality.

Background: Resource allocation planning for emergency medical services (EMS) systems determines appropriate resources including what paramedic qualification and how rapidly to respond to patients for optimal outcomes. The British Columbia Emergency Health Services implemented a revised response plan in 2013.

Methods: A pre- and post-methodology was used to evaluate the effect of the resource allocation plan revision on 24-hour mortality. All adult cases with evaluable outcome data (obtained through linked provincial health administrative data) were analyzed. Multivariable logistic regression was used to adjust for variations in other significant associated factors. Interrupted time series analysis was used to estimate immediate changes in level or trend of outcome after the start of the revised resource allocation plan implementation, while simultaneously controlling for pre-existing trends.

Results: The derived cohort comprised 562,546 cases (April 2012-March 2015). When adjusted for age, sex, urban/metro region, season, day, hour, and dispatch determinant, the probability of dying within 24 hours of an EMS call was 7% lower in the post-resource allocation plan-revision cohort (OR = 0.936; 95% CI: 0.886-0.989; p = 0.018). A subgroup analysis of immediately life-threatening cases demonstrated similar effect (OR = 0.890; 95% CI: 0.808-0.981; p = 0.019). Using time series analysis, the descending changes in overall 24-hour mortality trend and the 24-hour mortality trend in immediately life-threatening cases, were both statistically significant (p < 0.001).

Conclusion: Comprehensive, evidence-informed reconstruction of a provincial EMS resource allocation plan is feasible. Despite change in crew level response and resource allocation, there was significant decrease in 24-hour mortality in this pan-provincial population-based cohort.