Weight Loss Prior to Bariatric Surgery and 30-Day Mortality, Readmission, Reoperation, and Intervention: an MBSAQIP Analysis of 349,016 Cases.

Introduction: Despite preoperative weight loss being a common prerequisite to metabolic and bariatric surgery, its relationship to 30-day postoperative outcomes is unclear. The aim of this study was to assess whether preoperative weight loss is associated with 30-day postoperative quality outcomes in adults undergoing metabolic and bariatric surgery.

Methods: Retrospective cohort study assessing adults who underwent Roux-en-Y gastric bypass or sleeve gastrectomy in the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program Participant Use File, years 2015-2017. The relationship between preoperative weight loss and 30-day readmission, reoperation, mortality, intervention, and morbidity was assessed using multivariable logistic regression.

Results: Preoperative weight loss, body mass index loss, and percent weight loss were not associated with 30-day postoperative overall readmission, reoperation, mortality, or intervention (p > 0.01). Preoperative percent weight loss was associated with increased incidence of superficial surgical site infections (OR = 1.023, 95% CI 1.009-1.036; p = 0.001) and urinary tract infections (OR = 1.044, 95% CI 1.030-1.059; p < 0.001).

Conclusion: Weight loss prior to metabolic and bariatric surgery may not be necessary or safe for all patients. Unsafe weight loss prior to surgery may compromise nutrition status and lead to increased infection rates.