The clinical implications of ascites-stratified pre-liver transplant BMI on post-liver transplant prognosis of patients with nonalcoholic steatohepatitis

Abstract

Abstract Background & Aims: Determining the effects of pre-liver transplant (LT) BMI independent of underlying ascites on the post-LT outcomes of patients with nonalcoholic steatohepatitis (NASH) is needed to clarify the paradoxical and protective effects of obesity on post-LT endpoints. In order to accomplish this, we used graded severities of ascites to stratify the NASH-LT population and to perform an ascites-specific strata analysis with differing pre-LT BMI levels. Methods 2005–2019 United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research (STAR) database was queried to select patients with NASH, who were categorized into specific sets of ascites severity: no ascites (n = 1713), mild ascites (n = 5658), and moderate ascites (n = 4214). Then, BMI classification (underweight: <18.5, normal: 18.5–25, overweight: 25–30, obese: ≥30 kg/m²) was used to stratify each ascites-specific group and to compare to the post-LT mortality endpoints. Those under 18 years old and those who received living/multi-organ transplants were excluded. Results Among each ascites category, there were the following numbers of normal, underweight, overweight, and obese patients respectively; no ascites: 22, 10, 518, 964; mild ascites: 811, 41, 1662, 3144; and moderate ascites: 655, 30, 1233, 2296. Among those with moderate ascites, obese patients were at a lower risk of all-cause mortality compared to recipients with normal BMI (aHR 0.63 95%CI 0.47–0.86; case-incidence: 56.01 vs 67.04 per 1000 person-years). Furthermore, among those with moderate ascites, obese patients were less likely to experience graft failure (aHR 0.30 95%CI 0.13–0.67; case-incidence 7.35 vs 0.71 per 1000 person-years). However, similar reductions in the risks of all-cause mortality and graft failure among obese patients were not observed in the mild or no ascites groups. Conclusion The paradoxical effects of obesity in reducing the risks of all-cause death and graft failure appear to be in part modulated by ascites, as the obesity-related protective effects were observed only among NASH patients with significant ascites.