Geographic inequalities in prehospital critical care for cardiac arrest: a spatial analysis of deprivation and service configuration

BACKGROUND: Prehospital critical care is associated with improved outcomes after out-of-hospital cardiac arrest (OHCA) but appear less likely to attend patients in more deprived neighbourhoods. AIM: To determine how the geographical distribution of prehospital critical care bases influences the relationship between neighbourhood deprivation and attendance of prehospital critical care teams to OHCA patients. METHODS: Prehospital critical care was defined as any provider with clinical competencies beyond that of standard paramedics following Joint Royal Colleges Ambulance Liaison Committee guidelines and dispatched to critically ill patients. All OHCA patients treated by three neighbouring ambulance services in England between 2018 and 2023 were included. Data were aggregated at the neighbourhood level to produce continuous variables. Neighbourhood index of multiple deprivation decile was obtained. Data were mapped, geographical clusters identified using Moran's I, and spatial autocorrelation calculated. Explicit spatial modelling accounted for spatial dependence. RESULTS: Data from 57,601 patients were included, covering 9,639 neighbourhoods. Prehospital critical care attendance varied geographically, with a median neighbourhood attendance of 25.0%. Distance to the nearest prehospital critical care base was significantly associated with attendance. There was strong evidence of positive spatial autocorrelation and clustering of attendance. Accounting for spatial dependence removed the association with neighbourhood deprivation, whilst clinical variables, as well as distance to nearest prehospital critical care base and a daytime emergency call were the major drivers of prehospital critical care attendance. CONCLUSION: Observed inequalities in prehospital critical care attendance are explained by spatial factors and the geographic configuration of services rather than deprivation alone. Optimising the location of prehospital critical care assets represents an opportunity to reduce inequalities.