The Impact of Trauma Center Volume on Observed/Expected Mortality: Does Size Matter?

Abstract

Relationship between trauma center patient volume (TCV) and mortality remains inconclusive. Our aim was to determine the relationship between TCVs and observed/expected (O/E) all-cause mortality. This is the first study to evaluate the relationship between trauma center (TC) volumes and O/E all-cause mortality with no exclusion. Review of prospectively collected data from 94 TCs using the National Sample Program from the National Trauma Data Bank 2013. TCs were stratified into five groups based on TCV: <701, 701 to 1200, 1201 to 1700, 1701 to 2200, and >2200 yearly patient encounters. Chi-square and coefficient of determination were used for data analysis with a statistical significance defined as P-value < 0.05. A total of 139,324 trauma patients with blunt and penetrating injuries were evaluated from the National Sample Program. Of which, 63.6 per cent were male, 70.6 per cent white, and the average age was 41 years. The data were stratified by TCV into five groups with average O/Es ranging from 0.69 to 0.86 (P > 0.05). The coefficient of determination between TCV and O/E was r = 0.14 and r2 = 0.02. When controlling for Injury Severity Score, the correlation between mechanism of injury (blunt vs penetrating) and O/E mortality was r = 20.025. The group with the lowest average volumes had statistically significantly worse outcomes than the group with next higher volumes and also worse than the group with the highest volumes (Group 5, P = 0.04). Higher TC volumes correlated with higher injury severity and lower O/E mortality.

Is more better? Do statewide increases in trauma centers reduce injury-related mortality?

“…Studies suggest that higher patient volumes are associated with better outcomes because of center-level expertise. 5,[30][31][32] Adding trauma centers in areas without access may improve access to trauma care; conversely, adding trauma centers in areas without access issues may lead to dilution of expertise and lower patient volumes for those centers. 33,34 In Ohio, a statewide analysis demonstrated that a greater number of level I centers in a county or region was associated with slightly higher mortality compared with counties and regions with only one level I center.…”

The impact of teaching status on trauma center clinical outcomes in the United States

“…Generally, high TCV centers admit greater than 1200 patients annually, whereas low TCV centers admit less. [11] This higher volume could result in higher complication rates and cause the higher mortality rates. For instance, Tepas et al [12] evaluated the relationship between case volume and outcome as measured by mortality, and found a trend of increasing mortality with increasing volume, despite a consistent proportion of severe injury.…”

The impact of level of the American College of Surgeons Committee on Trauma verification and state designation status on trauma center outcomes

“…Both ACS and State Level 1 and 2 TCs had on average volumes above 1200 admissions per year, which is well above the 650-admission threshold determined by Nathens et al [11] for significantly improved outcomes. A similar study by Elkbuli et al [9] investigated the relationship between TCVs and observed/expected (O/E) all-cause mortality and found that higher TC volumes are correlated with higher injury severity and lower O/E mortality. This may indicate that TCV above a certain threshold is beneficial to patient outcomes and that the “threshold” effect is confirmed.…”

“…Generally, high TCV centers admit greater than 1200 patients annually while low TCV centers admit less. [9] A Shapiro-Wilk test was used to test for normality/skewness in TCV and injury distribution among ACS and State Level 1 and 2 TCs. To adjust for skewness in ISS data distribution among ACS and State Level 1 and 2 TCs, we used adjusted all-cause mortality (O/E mortality) as our primary outcome.…”