Risk stratification of serious adverse events after gastric bypass in the Bariatric Outcomes Longitudinal Database

Matthew L. MacIejewski, Deborah A. Winegar, Joel F. Farley, Bruce M. Wolfe, Eric J. Demaria

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


Background: There is now sufficient demand for bariatric surgery to compare bariatric surgeons and bariatric centers according to their postsurgical outcomes, but few validated risk stratification measures are available to enable valid comparisons. The purpose of this study was to develop and validate a risk stratification model of composite adverse events related to Roux-en-Y gastric bypass (RYGB) surgery. Methods: The study population included 36,254 patients from the Bariatric Outcomes Longitudinal Database (BOLD) registry who were 18-70 years old and had RYGB between June 11, 2007, and December 2, 2009. This population was randomly divided into a 50% testing sample and a 50% validation sample. The testing sample was used to identify significant predictors of 90-day composite adverse events and estimate odds ratios, while the validation sample was used to assess model calibration. After validating the fit of the risk stratification model, the testing and validation samples were combined to estimate the final odds ratios. Results: The 90-day composite adverse event rate was 1.48%. The risk stratification model of 90-day composite adverse events included age (40-64, <65), indicators for male gender, body mass index (50-59.9, <60), obesity hypoventilation syndrome, back pain, diabetes, pulmonary hypertension, ischemic heart disease, functional status, and American Society of Anesthesiology classes 4 or 5. Our final gastric bypass model was predictive (c-statistic =.68) of serious adverse events 90 days after surgery. Conclusions: With additional validation, this risk model can inform both the patient and surgeon about the risks of bariatric surgery and its different procedures, as well as enable valid outcomes comparisons between surgeons and surgical programs.

Original languageEnglish (US)
Pages (from-to)671-677
Number of pages7
JournalSurgery for Obesity and Related Diseases
Issue number6
StatePublished - Nov 2012

Bibliographical note

Funding Information:
Funding was provided by Surgical Review Corporation. This work was supported by the Office of Research and Development, Health Services Research, and Development Service, Department of Veterans Affairs. Dr. Maciejewski was also supported by a Research Career Scientist award from the Department of Veterans Affairs (RCS 10-391). The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs, Duke University, Surgical Review Corporation, or the University of North Carolina at Chapel Hill. ASMBS acknowledges the surgeons and facilities that enter data into BOLD for their participation in this important initiative.


  • Adverse events
  • Bariatric surgery
  • Gastric bypass
  • Mortality
  • Risk stratification
  • Roux-en-Y gastric bypass


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