Liver-related and extrahepatic events in patients with non-alcoholic fatty liver disease: a retrospective competing risks analysis

Background & Aim: Non-alcoholic fatty liver disease (NAFLD), and especially fibrotic non-alcoholic steatohepatitis, is associated with high risks of liver-related events (LRE) and extrahepatic events (EHE). We evaluated the competitive risk occurrence of LRE and EHE in a large cohort of biopsy-proven NAFLD stratified according to baseline severity of fibrosis. Methods: Two thousand one hundred thirty-five patients with biopsy-proven NAFLD were enrolled. Observed cumulative incidence functions (CIFs) were used to evaluate the risk of LRE and EHE; cause-specific Cox model and predicted CIFs were fitted to identify predictors of LRE and EHE. A replication cohort of NAFLD patients with liver fibrosis severity estimated by liver stiffness measurement by transient elastography was also enrolled. Results: Observed CIFs indicated that the 60-month probabilities of LRE and EHE were 0.2% and 3% in F0-F1, 2% and 3.8% in F2 and 9.7% and 6.4% in F3-F4 patients, respectively. The cause-specific Cox model indicated that in F0-F1 and F2 patients, age > 50 years (HR 2.7) was the only predictor of LRE, while age > 50 years (HR 2.96), previous cardiovascular events (CVE, HR 2.07), and previous extra-hepatic cancer (HR 2.36) were independent risk factors for EHE. In F3-F4 patients, age > 55 years (HR 1.73), obesity (HR 1.52), PLT < 150 000/mmc (HR 3.66) and log(GGT) (HR 1.77) were associated with LRE, while age > 55 years (HR 1.74) and previous CVE (HR 2.51) were independent predictors of EHE. Predicted CIFs for HE and EHE in F0-F1, F2 and F3-F4 patients stratified the risk of events. The results were externally replicated. Conclusion: The likelihood of EHE in NAFLD patients is relevant and increases according to the severity of liver fibrosis, while the risk of LRE is negligible in F0-F1, low but clinically relevant in F2 and high in F3-F4 patients.