Relationship of trauma patient volume to outcome experience: Can a relationship be defined?

Objectives: Five years experience recorded in a multi-institutional pediatric trauma registry was analyzed to define the relationship between case volume and outcome as measured by mortality. Methods: A total of 30,930 records with complete data were categorized by contributing hospital. Patients with fatal injury as indicated by an injury severity score of 75 or any abbreviated injury scale of 6 were excluded. Each center's experience was stratified by injury severity using injury severity score ≤ 15 as indicative of severe injury. Centers were then classified as low volume (LV, 100-500 cases), mid volume (MV, 501-1,000 cases), or high volume (HV, > 1,000 cases). Proportion of patients with severe injury (injury severity score > 15) and mortality were compared among groups using the χ² test with significance accepted at p < 0.05. Using the Pediatric Risk Indicator to adjust for mortality risk, the combined hospital experience of each volume group was further analyzed to assess performance with specific levels of increasing injury severity. Results: Findings demonstrated a trend of increasing mortality with increasing volume, despite a consistent proportion of severe injury. Risk adjusted mortality for each volume class indicates best outcome in the mid level group. Conclusions: Regardless of overall volume of patients encountered, there is a consistent proportion of severe injury. The increasing mortality with the most severe injuries seen in the high volume centers may reflect overdemand on resources.