Does it matter what a hospital is “high volume” for? Specificity of hospital volume-outcome associations for surgical procedures: analysis of administrative data*
- 1Department of Surgery, University of Toronto, 200 Elizabeth Street, 9EN-236A, Toronto, ON M5G 2C4, Canada
- 2Department of Surgery, University of Minnesota Cancer Center, MMC 806, 420, Delaware Street SE, Minneapolis, MN 55455, USA
- Correspondence to: D R Urbach Department of Surgery, University of Toronto, 200 Elizabeth Street, 9EN-236A, Toronto, ON M5G 2C4, Canada;
- Accepted 31 December 2004
Objective: To determine whether the improved outcome of a surgical procedure in high volume hospitals is specific to the volume of the same procedure.
Design and setting: Analysis of secondary data in Ontario, Canada.
Participants: Patients having an oesophagectomy, colorectal resection for cancer, pancreaticoduodenectomy, major lung resection for cancer, or repair of an unruptured abdominal aortic aneurysm between 1994 and 1999.
Main outcome measures: Odds ratio for death within 30 days of surgery in relation to the hospital volume of the same surgical procedure and the hospital volume of the other four procedures. Estimates were adjusted for age, sex, and comorbidity and accounted for hospital level clustering.
Results: With the exception of colorectal resection, 30 day mortality seemed to be inversely related not only to the hospital volume of the same procedure but also to the hospital volume of most of the other procedures. In some cases the effect of the volume of a different procedure was stronger than the effect of the volume of the same procedure. For example, the association of mortality from pancreaticoduodenectomy with hospital volume of lung resection (odds ratio for death in hospitals with a high volume of lung resection compared with low volume 0.36, 95% confidence interval 0.23 to 0.57) was much stronger than the association of mortality from pancreaticoduodenectomy with hospital volume of pancreaticoduodenectomy (0.76, 0.44 to 1.32).
Conclusion: The inverse association between high volume of procedure and risk of operative death is not specific to the volume of the procedure being studied.
Funding: This research was supported by an internal investigator initiated grant from the Institute for Clinical Evaluative Sciences and by the physicians of Ontario through the Physicians’ Services Incorporated Foundation. DRU is a career scientist of the Ontario Ministry of Health and Long-Term Care, Health Research Personnel Development Program.
Competing interests: None declared. Ethical approval: This research was conducted with the approval of the research ethics board of Sunnybrook and Women’s College Health Sciences Centre.
↵* This is a reprint of a paper that appeared in the BMJ, , –40.