Using geographic information systems (GIS) to assess response intervals for diffuse community bystander-driven...

The global trauma burden disproportionately affects low- and middle-income countries(LMICs), which lack robust emergency medical services(EMS). The Global Prehospital Consortium determined Tier-1 EMS response intervals are a priority for investigation. On-scene response intervals for professional ambulance-driven Tier-2 EMS vary by density of centralized ambulance dispatch sites per population, requiring costly infrastructure to improve response times. Community bystander-driven (Tier-1) systems are less costly with diffuse and non-centrally dispatched responders. Therefore, we hypothesized Tier-1 EMS response intervals to emergencies are not distance-related, due to the inherent diffusion of Tier-1 responders.

In 2016, Tanzania Rural Health Movement launched a Tier-1 lay first responder(LFR) program in Tanzania integrated with Beacon, a mobile emergency medical dispatch(EMD) platform. LFRs were provided with a two-day training course. Chief complaints, diurnal emergency variation, and response/triage/encounter intervals were prospectively recorded for analysis. GIS software (ArcGIS Pro 2.8) evaluated encounter latitude/longitude and distance from Mwanza city center, compared with response interval, using a logarithmic distribution for correlational analysis.

1273 entries were prospectively catalogued (2017-2024). 60 encounters lacked ≥67 % data compliance, 136 lacked GPS coordinates, and 89 geographic/time outliers were excluded, leaving 988 encounters for analysis (77.6 %). Of chief complaints, 81.0 % were road traffic injury-related. Median dispatch to on-scene arrival interval = 1 minute 4 seconds (IQR:36s-5m9s) and median on-scene arrival to triage decision interval = 1 minute 2 seconds (IQR:37s-2m32s) (n = 988). There was no correlation between log (response time interval) and log (distance from Mwanza center) (r = 0.028, p = 0.380) (n = 1012).

In this community-based EMS model, response times were rapid and not associated with geographic distance, highlighting the effectiveness of decentralized Tier-1 systems when combined with mobile dispatch technology. These findings support the scalability of low-cost, bystander-driven EMS networks in LMICs without reliance on traditional costly dispatch infrastructure, offering a promising strategy to address the global trauma burden.