Obesity is an Independent Risk Factor for Mortality in Otherwise Healthy Patients After Hepatectomy

Background: Obesity is often associated with comorbidities that limit remnant liver recovery after hepatectomy. The extent to which obesity, in the absence of comorbidities, impacts surgical risk after hepatectomy is unknown. We hypothesized that an obese population without major comorbidities would not be at increased risk of adverse outcomes after hepatectomies.

Methods: We performed a retrospective analysis identifying patients who underwent hepatectomies from the American College of Surgeons National Surgical Quality Improvement Program data set 2005-2017. Outcomes of interest included the following: mortality, any morbidity, critical care complications, and failure to discharge home. Body mass index (BMI) was the primary variable of interest, grouped as ≥35 and <35 based on bivariate tests of associations with candidate cut-off points. In attempt to isolate the effect of obesity on outcomes among patients "without major comorbidities" (WOC), we included patients without diabetes, chronic obstructive pulmonary disease, renal insufficiency, and nonsmokers; remaining patients were grouped as "with major comorbidities" (WC). Multivariable logistic regression was used to test whether obesity is independently associated with the outcomes of interest after adjustment for other covariates.

Results: A total of 36,396 patients were included. There were 13,754 patients in the WOC group and 22,642 in the WC group. Among patients in the WOC group, the adjusted odds of mortality were 2.2 times higher for patients with a BMI ≥35 versus a BMI <35. Among the patients in the WC group, a BMI ≥35 was not a statistically significant predictor of mortality after adjustment for other covariates. Obese patients had increased odds of each outcome among the WOC group.

Conclusions: Our hypothesis was refuted by these data. In fact, the adverse effect of obesity was more evident among healthy patients.