Injured patients presenting in shock are at high risk of mortality despite numerous efforts to improve resuscitation. Identifying differences in outcomes among centers for this population could yield insights to improve performance. We hypothesized that trauma centers treating higher volumes of patients in shock would have lower risk-adjusted mortality.
We queried the Pennsylvania Trauma Outcomes Study from 2016 to 2018 for injured patients ≥16 years of age at Level I&II trauma centers who had an initial systolic blood pressure (SBP) of <90 mmHg. We excluded patients with critical head injury (abbreviated injury score [AIS] head ≥5) and patients coming from centers with a shock patient volume of ≤10 for the study period. The primary exposure was tertile of center-level shock patient volume (low, medium, or high volume). We compared risk-adjusted mortality by tertile of volume using multivariable Cox proportional hazards model incorporating age, injury severity, mechanism, and physiology.
Of 1,805 included patients at 29 centers, 915 (50.7%) died. The median annual shock trauma patient volume was 9 patients for low volume centers, medium 19.5, and high 37. Median ISS was higher at high volume compared to low volume centers (22 vs 18, p <0.001). Raw mortality was 54.9% at high volume centers, 46.7% for medium, and 42.9% for low. Time elapsed from arrival to emergency department (ED) to the operating room (OR) was lower at high volume than low volume centers (median 47 vs 78 min) p = 0.003. In adjusted analysis, hazard ratio for high volume centers (referenced to low volume) was 0.76 (95% CI 0.59-0.97, p = 0.030).
After adjusting for patient physiology and injury characteristics, center-level volume is significantly associated with mortality. Future studies should seek to identify key practices associated with improved outcomes in high-volume centers. Furthermore, shock patient volume should be considered when new trauma centers are opened.

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