Systematic review with meta-analysis: post-operative complications and mortality risk in liver transplant candidates with obesity

Background: International guidelines rate class III (morbid) obesity (body mass index [BMI]= 40 kg/m(2)) as a relative contraindication for liver transplantation (LT) requiring further research. Moreover, data on the mortality risk in candidates with a BMI: 3034.9 and 35-39.9 kg/m(2) (class I and class II obesity, respectively) are weak. Aim: To compare post-operative complications and mortality risks in all obese candidates vs candidates with a BMI: 18.5-29.9 (normal/overweight) assumed as controls. Methods: We searched the Cochrane library, PubMed, Scopus, Web-of-Science and article reference lists, restricted to the English language, and selected cohort studies analysing the following outcomes: all-causes mortality (at 30 days, 1-2-3-5 years), post-operative and cardiopulmonary complications, hospital and intensive care unit (ICU) length of stay. Two reviewers independently extracted the studies data and a third one resolved discrepancies. Results: Twenty-four studies comprising 132 162 patients met the inclusion criteria. As compared to controls, mortality risk was increased at all time-periods (except at 3 years) for a BMI >= 40, at 30 days for a BMI: 30-34.9 and in none of the considered time-periods for a BMI: 35-39.9. Post-operative complications were significantly higher for a BMI>30 and 30-34.9. Due to the shortage/absence of data, we evaluated cardiopulmonary complications, hospital and ICU length of stay only in the BMI >= 30 category. In these patients, only cardiopulmonary complications were increased as compared to controls. Conclusions: Morbid obesity has an impact on patients' survival after LT. However, since even a BMI>30 increases post-transplant complications, new strategies should be included in the LT programme to favour weight loss in all obese candidates.