Body Weight Parameters are Related to Morbidity and Mortality After Liver Transplantation: A Systematic Review and Meta-analysis

Background. Weight gain and obesity are well-known clinical issues in liver transplantation (LTx). However, their impacts on patient outcomes remain unclear, as only the impact of pre-LTx body mass index (BMI) on survival has been meta-analyzed. We summarized and synthesized the evidence on pre- and post-LTx body weight parameters' relations with post-LTx outcomes such as survival, metabolic and cardiovascular comorbidities, and healthcare utilization. Methods. We followed the Cochrane Handbook for Systematic Reviews of Interventions' recommendations. Quality was assessed via a 19-item instrument. Odds ratios and 95% confidence intervals were calculated for outcomes investigated in >= 5 studies. Results. Our meta-analysis included 37 studies. Patients with pre-LTx BMI >= 30 kg/m(2) and BMI >= 35 kg/m(2) had lower overall survival rates than those with pre-LTx normal weight (72.6% and 69.8% versus 84.2%; P = 0.02 and P = 0.03, respectively). Those with pre-LTx BMI >= 30 kg/m(2) had worse overall graft survival than normal weight patients (75.8% and 85.4%; P = 0.003). Pre-LTx BMI and pre-LTx overweight were associated with new-onset diabetes (P <0.001 and P = 0.015, respectively), but post-LTx BMI showed no relationship. No associations were evident with healthcare utilization. Conclusions. Patients with BMI values >= 30 kg/m(2) had worse patient and graft survival than those with normal weight. Few of the reviewed studies examined post-LTx body weight parameters or other relevant outcomes such as cardiovascular comorbidities. High heterogeneity as well as diverse definitions and operationalizations of measurement and outcomes severely impeded comparability.