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The impact of interhospital transfer on mortality benchmarking at Level III and IV trauma centers: A step toward
Daniel N Holena1, Elinore J Kaufman, Justin Hatchimonji
1From the Division of Traumatology, Surgical Critical Care and Emergency Surgery (D.N.H., E.J.K., J.H., B.P.S., P.M.R.), Center for Clinical Epidemiology and Biostatistics (D.N.H., J.H., R.X., M.K.D., D.J.W.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia; Pennsylvania Trauma Systems Foundation (T.E.W.), Harrisburg; Department of Emergency Medicine (M.K.D.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia; and Department of Emergency Medicine (B.G.C.), Kimmel School of Medicine at the Thomas Jefferson University, Philadelphia, Pennsylvania.
Background:
Many injured patients presenting to Level III/IV trauma centers will be transferred to Level I/II centers, but how these transfers influence benchmarking at Level III/IV centers has not been described. We hypothesized that the apparent observed to expected (O:E) mortality ratios at Level III/IV centers are influenced by the location at which mortality is measured in transferred patients.
Methods:
We conducted a retrospective study of adult patients presenting to Level III/IV trauma centers in Pennsylvania from 2008 to 2017. We used probabilistic matching to match patients transferred between centers. We used a risk-adjusted mortality model to estimate predicted mortality, which we compared with observed mortality at discharge from the Level III/IV center (O) or observed mortality at discharge from the Level III/IV center for nontransferred patients and at discharge from the Level I/II center for transferred patients (O).
Results:
In total, 9,477 patients presented to 11 Level III/IV trauma centers over the study period (90% white; 49% female; 97% blunt mechanism; median Injury Severity Score, 8; interquartile range, 4-10). Of these, 4,238 (44%) were transferred to Level I/II centers, of which 3,586 (85%) were able to be matched. Expected mortality in the overall cohort was 332 (3.8%). A total of 332 (3.8%) patients died, of which 177 (53%) died at the initial Level III/IV centers (O). Including posttransfer mortality for transferred patients in addition to observed mortality in nontransferred patients (O) resulted in worse apparent O:E ratios for all centers and significant differences in O:E ratios for the overall cohort (O:E, 0.53; 95% confidence interval, 0.45-0.61 vs. O:E, 1.00, 95% confidence interval, 0.92-1.11; p < 0.001).
Conclusion:
Apparent O:E mortality ratios at Level III/IV centers are influenced by the timing of measurement. To provide fair and accurate benchmarking and identify opportunities across the continuum of the trauma system, a system of shared attribution for outcomes of transferred patients should be devised.
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