The Clinical Relevance of Differentiating Nonalcoholic Steatohepatitis From Simple Steatosis

Risk of Cirrhosis and Hepatocellular Cancer in Patients With NAFLD and Normal Liver Enzymes

BACKGROUND AND AIMS

The long-term risk of disease for patients with nonalcoholic fatty liver disease (NAFLD) in the absence of elevated enzymes is unclear. We conducted a retrospective cohort study using the Corporate Data Warehouse of the Veterans Health Administration.

APPROACH AND RESULTS

We classified patients into three groups: patients with steatosis/normal alanine aminotransferase (ALT), steatosis/elevated ALT, and no steatosis/normal ALT. We examined incidence rates for cirrhosis and hepatocellular carcinoma (HCC) and conducted cause-specific hazard models to evaluate the risk of cirrhosis and HCC. We identified 3,522 patients with steatosis/normal ALT, 15,419 patients with steatosis/elevated ALT, and 9,267 patients with no steatosis/normal ALT. The mean age in each group was 58.9, 54.7 and 59.3 years, respectively; over 90% were men. Compared to patients with hepatic steatosis/normal ALT, those with steatosis/elevated ALT were younger and more likely to be obese (both P < 0.01). In patients with steatosis/normal ALT, the incidence rates of cirrhosis and HCC were 1.22 (95% confidence interval [CI]: 0.83-1.74) and 0.20 (95% CI: 0.06-0.46) per 1,000 person-years, respectively; this was lower than in patients with steatosis/elevated ALT (cirrhosis: 3.85; 95% CI: 3.50-4.23, and HCC: 0.37; 95% CI: 0.26-0.49). Patients with steatosis/elevated ALT had a higher risk of developing cirrhosis (adjusted hazard ratio: 3.37; 95% CI:  2.34-4.86; P < 0.01) than patients with steatosis/normal ALT; they also had a higher risk of HCC, although it did not reach statistical significance (hazard ratio: 2.07; 95% CI: 0.82-5.28; P = 0.13). The risk of cirrhosis and HCC in patients with steatosis/normal ALT and those without steatosis was not significantly different.

CONCLUSIONS

Patients with hepatic steatosis with persistently normal ALT are at lower risk for cirrhosis compared to those with steatosis and elevated ALT and not different from the risk in a clinical cohort without hepatic steatosis.

The diagnostic conundrum in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver alteration worldwide. It encompasses a spectrum of disorders that range from simple steatosis to a progressive form, defined non-alcoholic steatohepatitis (NASH), that can lead to advanced fibrosis and eventually cirrhosis and hepatocellular carcinoma. On liver histology, NASH is characterized by the concomitant presence of significant fat accumulation and inflammatory reaction with hepatocellular injury. Until now, liver biopsy is still required to differentiate simple steatosis from NASH and evaluate the degree of liver fibrosis. Unfortunately, this technique has well-known limitations, including invasiveness and expensiveness. Moreover, it may be biased by sampling error and intra- or inter-observed variability. Furthermore, due to the increasing prevalence of NAFLD worldwide, to program a systematic screening with liver biopsy is not imaginable. In recent years, different techniques were developed and validated with the aim of non-invasively identifying NASH and assess liver fibrosis degrees. The non-invasive tests range from simple blood-tests analyses to composite scores and complex imaging techniques. Nevertheless, even if they could represent cost-effective strategies for diagnosing NASH, advanced fibrosis and cirrhosis, their accuracy and consequent usefulness are to be discussed. With this aim, in this review the authors summarize the current state of non-invasive assessment of NAFLD. In particular, in addition to the well-established tests, the authors describe the future perspectives in this field, reporting the latest tests based on OMICS, gut-miocrobioma and micro-RNAs. Finally, the authors provide an accurate assessment of how these non-invasive tools perform in clinical practice depending on the clinical context, with the aim of giving the clinicians a useful tool to try to resolve the diagnostic conundrum of NAFLD.