Introduction: Version 2 of the Needs-Based Assessment of Trauma Systems (NBATS) tool quantifies the impact of an additional trauma center on a region. This study applies NBATS-2 to a system where an additional trauma center was added to compare the tool's predictions to actual patient volumes.
Methods: Injury data were collected from the trauma registry of the initial (legacy) center and analyzed geographically using ArcGIS. From 2012 to 2014 ("pre-"period), one Level 1 trauma center existed. From 2016 to 2018 ("post-"period), an additional Level 2 center existed. Emergency medical service (EMS) destination guidelines did not change and favored the legacy center for severely injured patients (Injury Severity Score (ISS) >15). NBATS-2 predicted volume was compared to the actual volume received at the legacy center in the post-period.
Results: 4068 patients were identified across 14 counties. In the pre-period, 72% of the population and 90% of injuries were within a 45-minute drive of the legacy trauma center. In the post-period, 75% of the total population and 90% of injuries were within 45 minutes of either trauma center. The post-predicted volume of severely injured patients at the legacy center was 434, but the actual number was 809. For minor injuries (ISS £15), NBATS-2 predicted 581 vs. 1677 actual.
Conclusion: NBATS-2 failed to predict the post-period volume changes. Without a change in EMS destination guidelines, this finding was not surprising for severely injured patients. However, the 288% increase in volume of minor injuries was unexpected. NBATS-2 must be refined to assess the impact of local factors on patient volume.
Keywords: geographic modeling; trauma centers; trauma systems.