Hospitals with higher volumes of emergency general surgery patients achieve lower mortality rates: A case for establishing designated centers for emergency general surgery

Background: Higher volume has been associated with lower mortality for several surgical diseases. It is not known if this relationship exists in the management of Emergency General Surgery (EGS). Our hypothesis was that EGS patients treated at hospitals with higher EGS volume experienced lower mortality rates than those treated at low-volume hospitals. Methods: This was a retrospective analysis of 2010 National Inpatient Sample data, maintained by the Agency for Healthcare Quality and Research as a representative national sample of inpatients. Patients with EGS diseases were identified using American Association for the Surgery of Trauma definitions using ICD-9 codes (2,640,725 patients from 943 hospitals). Multivariable hierarchical logistic regression model was used to estimate the risk-standardized mortality rate (RSMR) for each hospital, adjusted for patient (age, sex, race, ethnicity, insurance type, socioeconomic status, comorbidities) and hospital (region, location, bed size, teaching status, ownership) characteristics. A cubic spline regression model with 4 knots was used to identify the volume associated with low mortality rates. Results: The volume of EGS patients treated was inversely associated with hospital mortality rate. RSMR in hospitals in the highest quintile of volume (median, 7424 patients) was 1.62% (95% CI: 1.61-1.64%); at hospitals in the lowest quintile of volume (median, 68 patients), it was 6.1% (95% CI: 6.0-6.2%) (p < 0.0001). Mortality rate stabilized at an annual volume of 688 (95% CI: 554-753) patients. The mortality rate in hospitals that treated fewer than 688 patients was 5.0% (95% CI: 4.8-5.1%), compared to 1.99% (95% CI: 1.96-2.01%) at those that treated 688 or more patients (p < 0.0001). Conclusion: EGS patients treated at hospitals with a higher volume of EGS patients experienced lower mortality rates, with a possible threshold of 688 patients per year. A regionalized system of EGS care where complex patients are treated at large-volume centers may improve patient outcomes. Level of Evidence: Therapeutic study, level III.