Metabolic dysfunction-associated fatty liver disease and liver function markers are associated with Crohn's disease...

Metabolic dysfunction-associated fatty liver disease (MAFLD) is recently recognized as a condition featured with metabolic dysfunctions in liver. It has been supposed that MAFLD might contribute to the development of IBD, but evidence from prospective cohort studies is lacking and inconclusive.

A total of 221,546 females and 183,867 males from the UK Biobank cohort enrolled in 2006-2010 were included to examine whether MAFLD and liver function markers were related to incident IBD. MAFLD was identified based on hepatic steatosis defined by fatty liver index plus the prevalence of overweight, type 2 diabetes mellitus, or at least two metabolic abnormalities. Biomarker related to liver function (albumin [ALB], alkaline phosphatase [ALP], alanine transaminase [ALT], aspartate transaminase [AST]; gamma-glutamyl transferase [GGT], total bilirubin [TB], total protein [TP]) was measured using colorimetric or enzymatic assays. The incidence of IBD was ascertained based on primary care and inpatient records. Cox proportional hazard model was used to estimate hazard ratios (HRs) with 95% confidence intervals (CI) for the magnitude of their associations.

With a mean follow-up of 12.1 years, 2228 incident IBD cases were documented. We identified 150,385 individuals with MAFLD at baseline and 86% participants' circulating liver function markers were within the normal range. Participants with MAFLD were associated with a 12% (HR 1.12, 95% CI 1.03, 1.23, p = 0.012) increased risk of IBD compared with those without MAFLD at baseline; the association was stronger (p-_{Heterogeneity} = 0.006) with Crohn's disease (HR 1.35, 95% CI 1.15, 1.59, p < 0.001) than ulcerative colitis (HR 1.03, 95% CI 0.93, 1.15, p = 0.57). As for the serum liver function markers, the HRs of IBD for per 1-SD increment in ALB, ALP, AST, and TB concentration were 0.86 (95% CI 0.83, 0.90, p < 0.001), 1.18 (95% CI 1.13, 1.24, p < 0.001), 0.95 (95% CI 0.91, 0.99, p = 0.027), 0.92 (95% CI 0.87, 0.96, p < 0.001), respectively. We did not observe significant associations of GGT and TP with IBD.

Individuals with MAFLD were at increased risk of developing IBD, especially CD, but not UC. Circulating levels of liver function biomarkers as the surrogate indicators of MAFLD were also associated with IBD risk.