Volume-outcome Relationships and Other Influences of Outcome in Bariatric Surgery – Justification of the Current Paradigm

Introduction: With the incidence of morbid obesity in the United States increasing at a rapid rate, bariatric surgical practices have continued to flourish. Recent years have seen the establishment by various professional organizations of credentialing processes, centers-of-excellence programs and fellowship training positions. Many of these processes grant privileges to bariatric surgeons based on case volume, with the expectation that higher case volume results in improved outcomes. The effect of center-of-excellence status and of a fellowship training program has not previously been examined. This study examines volume-outcome relationships and other influences of outcome of bariatric surgery in the United States over a nine year period.
Methods and Procedures: Data were obtained from the Nationwide Inpatient Sample, the largest all-payer discharge database in the United States, from 1998 to 2006. Quantification of patients’ comorbidities was made using the Charlson Index. Using logistic regression modeling, annual case volumes were correlated with institutions’ center-of-excellence status and fellowship training program status. Risk-adjusted outcome measures were calculated for these hospital-level parameters.
Results: A total of 496,267 bariatric operations were recorded for the study period. Adjusting for comorbidities, greater bariatric case volume was seen to result in statistically significant improvements in the incidence of in-hospital mortality. Strong beneficial trends in rates of pulmonary embolism, cardiac complications, intra-abdominal collections and requirement for laparotomy were noted to be associated with increasing case volume. Hospitals with a fellowship training program had a risk-adjusted significant improvement in rates of venous thromboembolism and rates of splenectomy. Center-of-excellence status, whether affiliated with the American College of Surgeons or with the Surgical Review Corporation / American Society for Metabolic and Bariatric Surgery, did not have any independent effect on outcome.
Conclusions: For the first time, the hypothesized positive volume-outcome relationship of bariatric surgery has been shown without artificially categorizing hospitals to case-volume groups. Institutions with a fellowship training program have also been shown, in part, to have improved outcomes. The concept of volume-dependent center-of-excellence programs been validated, though no independent effect of the credentialing process is noted. The current paradigm of assuming improved outcomes as a result of the above parameters has now been justified.

Session: Podium Presentation

Program Number: S123

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