December 24, 2013Open Access
Hospital Volume and Operative Mortality in the Modern Era
Key Result
Higher hospital operative volume was associated with significantly lower mortality rates across 8 major procedures, and this strong inverse relationship persists in the modern era.
Study Design
Type
Observational (n=3,282,127)
Multicenter
Yes
Structured PICO
Does treatment at higher volume hospitals reduce operative mortality in patients undergoing major gastrointestinal, cardiac, or vascular procedures?
P
Population
3,282,127 Medicare patients who underwent 1 of 8 gastrointestinal, cardiac, or vascular procedures between 2000 and 2009.
E
Exposure
Treatment at higher volume hospitals (stratified into quintiles of operative volume)
C
Comparator
Treatment at lower volume hospitals
O
Outcome
Operative mortalityhard clinical
Higher hospital surgical volume remains strongly associated with lower operative mortality across major procedures, with the effect persisting or strengthening over a recent 10-year period despite overall improvements in surgical safety.
Abstract
OBJECTIVE: To determine whether the relationship between hospital volume and mortality has changed over time. BACKGROUND: It is generally accepted that hospital volume is associated with mortality in high-risk procedures. However, as surgical safety has improved over the last decade, recent evidence has suggested that the inverse relationship has diminished or been eliminated. METHODS: Using national Medicare claims data from 2000 through 2009, we examined mortality among 3,282,127 patients who underwent 1 of 8 gastrointestinal, cardiac, or vascular procedures. Hospitals were stratified into quintiles of operative volume. Using multivariable logistic regression models to adjust for patient characteristics, we examined the relationship between hospital volume and mortality, and assessed for changes over time. We performed sensitivity analyses using hierarchical logistic regression modeling with hospital-level random effects to confirm our results. RESULTS: Throughout the 10-year period, a significant inverse relationship was observed in all procedures. In 5 of the 8 procedures studied, the strength of the volume-outcome relationship increased over time. In esophagectomy, for example, the adjusted odds ratio of mortality in very low volume hospitals compared to very high volume hospitals increased from 2.25 95% confidence interval (CI): 1.57-3.23 in 2000-2001 to 3.68 (95% CI: 2.66-5.11) in 2008-2009. Only pancreatectomy showed a notable decrease in strength of the relationship over time, from 5.83 (95% CI: 3.64-9.36) in 2000-2001, to 3.08 (95% CI: 2.07-4.57) in 2008-2009. CONCLUSIONS: For all procedures examined, higher volume hospitals had significantly lower mortality rates than lower volume hospitals. Despite recent improvements in surgical safety, the strong inverse relationship between hospital volume and mortality persists in the modern era.