INSTITUTION AND PER-SURGEON VOLUME VERSUS SURVIVAL OUTCOME IN PENNSYLVANIA TRAUMA CENTERS

BACKGROUND: The American College of Surgeons recommends minimum patien t volumes for trauma centers and surgeons. Those numbers, however, are largely based on results from studies of surgical (but not trauma) re lationships between volume and outcome. METHODS: Using stepwise regres sion, relationships were sought between measures of patient volume per trauma center and per surgeon and a severity-controlled measure of su rvival outcome (W), For significant z values, W is the number of addit ional (or fewer) survivors, per 100 patients treated, than expected fr om ASCOT norms, W = 0 when z is nonsignificant. Data are from patients admitted in 1988 and 1989 to accredited Pennsylvania trauma centers. RESULTS: The relationships found for all patients and for adult blunt- injured patients are W = -0.3312 + 0.0200 (N-SER(B)/SURG) and W = -0.3 638 + 0.0248 (N-SER(B)/SURG), respectively, where N-SER/SURG is the nu mber of seriously injured patients treated annually per surgeon and N- SER(B)/SURG is the number of adult patients with serious blunt injurie s treated annually per surgeon, Serious injury was defined, using the Injury Severity Scale, as greater than or equal to 13 or, using the Ab breviated injury Scale, as a head injury of greater than or equal to 3 . The relationships explained 36% and 61% of the variance in W (R(2) f or all patients and adult blunt-injured patients, respectively. To ach ieve normative survival (W = 0), 95% confidence Intervals suggest that a trauma surgeon should treat at least 35 seriously injured patients per year and at least 28 adult patients with serious blunt injury annu ally. No volume-related variable was a significant contributor to pred ictions of W for adult patients with penetrating injuries or for pedia tric patients. CONCLUSIONS: These results support the regionalization of trauma care by affirming that increased per-surgeon experience in t he treatment of seriously injured patients is associated with improved outcomes and help define the minimum experience needed to achieve nor mative survival. Prospective study of the relationship between volume and survival and other outcomes is required.