Volume-Mortality Relationships during Hospitalization with Severe Sepsis Exist Only at Low Case Volumes.

Abstract

Volume-outcome associations have been demonstrated in conditions with high morbidity and mortality; however, the existing literature regarding such associations in sepsis is not definitive. To test the hypothesis that annual hospital severe sepsis case volume is associated with mortality during admissions with severe sepsis in teaching and nonteaching hospitals. This work was a retrospective cohort study of administrative data from the South Carolina State Inpatient Database using multivariate logistic regression and case mix adjustment. In the calendar year 2010, 9,815 patients were admitted with severe sepsis or septic shock. Hospitals were stratified into low- (0-75 cases/yr, n = 26), intermediate- (76-300 cases/yr, n = 19), and high (>300 cases/yr, n = 12) -volume tertiles. Patients admitted to hospitals with a low annual case volume for sepsis had higher adjusted odds of dying before discharge (odds ratio, 1.56; 95% confidence interval, 1.25-1.94) compared with patients admitted to high-volume hospitals. Hospitalization at intermediate-volume hospitals was not associated with a difference in mortality (odds ratio, 0.99; 95% confidence interval, 0.90-1.09) compared with high-volume hospitals. There was no difference between the mortality rates of intermediate- and high-volume hospitals at different severity of illness quartiles. Hospital length of stay differed significantly by hospital case volume (low = 8.0, intermediate = 12.7, high = 14.9 [d]; P < 0.0001). Hospitals with low annual sepsis case volume are associated with higher mortality rates, whereas hospitals with intermediate sepsis case volumes are associated with similar mortality rates compared with hospitals with high case volumes.