Screening for Severe Hepatic Fibrosis by FibroScan in a Population Presenting a Severe Psychiatric Disorder Under Treatment for at Least Two Years.

Patients with psychiatric illness are often exposed to an increase risk of mortality compared to the general population: a reduction of life expectancy between 7 and 24 years has been described . Somatic illnesses explain 60% of this excess of mortality, particularly cardiovascular diseases . Notably, patients with chronic psychiatric disorders, such as depression, bipolar disorders or schizophrenia are more frequently exposed to metabolic syndrome. A recent meta-analysis showed that patients with severe mental illness had a RR of 1.58 (1.35-1.86) of developing metabolic syndrome.

Steatosis, or fat excess in hepatocytes defines NAFLD (non-alcoholic fatty liver disease). NAFLD is a spectrum of liver illnesses associated with metabolic syndrome. Within NAFLD, NASH (non-alcoholic steatohepatitis) occurs in about 5 % of the cases, liver inflammation and/or fibrosis being associated to steatosis: Survival is then impaired, notably with a specific risk of cirrhosis in 20% of the patients with NASH and 3 % of patients with NAFLD . Hepatocarcinoma is a complication of cirrhosis but it may be observed in the absence of cirrhosis in nearly 30% of the cases. Its prevalence is progressively increasing, from 20 to 27%. It will probably be the leading cause of liver transplantation in the next years Otherwise, patients with NAFLD are also exposed to non-liver related complications: cardiovascular risk is higher in this population and is the main risk of mortality.

Although NAFLD is a frequent disease, it is yet generally misdiagnosed today, essentially because of the lack of symptoms and of systematic screening. Furthermore, it is key to diagnose the evolutionary stage: pure NAFLD, NASH and stage of fibrosis. The liver biopsy remains the gold standard, despite its limitations linked to the sample variability and the differences in interpretation even between expert pathologists.

However, specific risks associated with this procedure, such as bleeding and even a marginal risk of death have been described. Furthermore, liver biopsy is costly. All these arguments explain the difficulty to apply this invasive strategy in screening in the general population. That's why different methods, based on non-invasive tests, were developed to diagnose fibrosis - the main prognostic factor - and more recently in a more preliminary way to assess steatosis and inflammation. Two main methods are used to evaluate fibrosis stage: serum biomarkers and liver stiffness. Serum biomarkers are non-parametric (for example NAFLD fibrosis score, Fib4, Forns score and more recently, eLIFT.) or parametric (for example FibroTest, FibroMeter.). Liver stiffness is mainly assessed by FibroScan: it is easily available, and reproducible. It was largely validated in different liver diseases, including NAFLD. Steatosis is simultaneously evaluated, thanks to CAP (controlled attenuation parameter.). Strategies based on the associations of different markers have been evaluated to increase sensibility and specificity of each method taken alone to assess fibrosis. Specific combinations of elastometry and biomarkers have emerged, such as FibroMeterVCTE, and FAST.

In the psychiatric field, NAFLD screening may be important to help to identify patients at liver risk and also at a potential metabolic risk especially since a specific management is available.