The impact of non-alcoholic fatty liver disease and liver fibrosis on adverse clinical outcomes and mortality in patients with chronic kidney disease: a prospective cohort study using the UK Biobank.

BACKGROUND: Chronic kidney disease (CKD) and non-alcoholic fatty liver disease (NAFLD) frequently co-exist. We assess the impact of having NAFLD on adverse clinical outcomes and all-cause mortality for people with CKD. METHODS: A total of 18,073 UK Biobank participants identified to have CKD (eGFR < 60 ml/min/1.73 m2 or albuminuria > 3 mg/mmol) were prospectively followed up by electronic linkage to hospital and death records. Cox-regression estimated the hazard ratios (HR) associated with having NAFLD (elevated hepatic steatosis index or ICD-code) and NAFLD fibrosis (elevated fibrosis-4 (FIB-4) score or NAFLD fibrosis score (NFS)) on cardiovascular events (CVE), progression to end-stage renal disease (ESRD) and all-cause mortality. RESULTS: 56.2% of individuals with CKD had NAFLD at baseline, and 3.0% and 7.7% had NAFLD fibrosis according to a FIB-4 > 2.67 and NFS ≥ 0.676, respectively. The median follow-up was 13 years. In univariate analysis, NAFLD was associated with an increased risk of CVE (HR 1.49 [1.38-1.60]), all-cause mortality (HR 1.22 [1.14-1.31]) and ESRD (HR 1.26 [1.02-1.54]). Following multivariable adjustment, NAFLD remained an independent risk factor for CVE overall (HR 1.20 [1.11-1.30], p < 0.0001), but not ACM or ESRD. In univariate analysis, elevated NFS and FIB-4 scores were associated with increased risk of CVE (HR 2.42 [2.09-2.80] and 1.64 [1.30-2.08]) and all-cause mortality (HR 2.82 [2.48-3.21] and 1.82 [1.47-2.24]); the NFS score was also associated with ESRD (HR 5.15 [3.52-7.52]). Following full adjustment, the NFS remained associated with an increased incidence of CVE (HR 1.19 [1.01-1.40]) and all-cause mortality (HR 1.31 [1.13-1.52]). CONCLUSIONS: In people with CKD, NAFLD is associated with an increased risk of CVE, and the NAFLD fibrosis score is associated with an elevated risk of CVE and worse survival.