NASH refers to the most advanced stage of non-alcoholic fatty liver disease, involving a combination of fat accumulation, inflammation and lesions in the hepatocyte cells. In particular, these alterations can lead to cirrhosis or liver cancer.
Associated with sedentary lifestyles and poor eating habits, this epidemic has been silently spreading across developed countries.
Prevention and treatment of the risk factors are the only therapeutic solutions currently available.
Non-alcoholic fatty liver disease (NAFLD1) and its most advanced stage, non-alcoholic steatohepatitis (NASH2), are consistent with an accumulation of fat of over 5% in the liver cells. Hence their name “fatty liver diseases”.
In the case of NASH, excess lipids cause inflammation and tissue lesions which can lead to fibrosis (scarring), similar to the symptoms found in alcoholic cirrhosis.
In correlation with the diabetes and obesity pandemic, the number of cases of NAFLD and NASH have been constantly increasing in industrialized countries. The prevalence of NAFLD is therefore predicted to be higher than 25% on a global scale (Europe and USA 24%, Asia 27-37%) and that of NASH will exceed 9% on average.
Current forecasts mainly predict growth of over 21% for NAFLD and over 63% for NASH by 2030, contributing to a 178% increase in the number of deaths linked to liver disorders.
NASH mainly presents in patients who are overweight, who are suffering from type 2 diabetes, an insulin resistance or dyslipidemia.
The main risk factors are:
BMI higher than 25 kg/m².
> 6.1 mmol/L fasting.
> 1.7 mmol/L fasting.
waist circumference greater than 88 cm for women and 102 cm for men.
< 0.5 g/l for women and < 0.4 g/L for men.
In general, patients with NAFLD or NASH do not present with symptoms, however some may feel fatigued or generally unwell or may experience abdominal discomfort. Over time, signs of portal hypertension and cirrhosis may appear. These symptoms signal the first clinical signs of the development of a more advanced stage of NASH: hepatic deficiency, hepatocellular decompensation or carcinoma.
NASH also contributes to the etiology of cardiovascular diseases, diabetes and certain non-hepatic cancers.
Often detected late due to the lack of characteristic symptoms, a NASH diagnosis relies on physical and biological examinations in the first instance, which can reveal an increase in liver volume and a rise in certain enzymatic levels (GGTs and transaminases). In suspected cases, the diagnosis can be confirmed by means of a biopsy, where the hepatic tissues can be analysed and a determination can be made as to whether it is a case of NASH or alcoholic cirrhosis.
Preventing or slowing down the development of NASH is the best approach in order to avoid the onset of other problems. There is no direct treatment: the aim is to eliminate the potential causes and risk factors, such as overweight, diabetes and hyperlipidemia.
This objective is achieved by adopting a healthier lifestyle and improving eating habits, as well as by practising physical exercise. A medico-psychological support plan may also be prescribed in addition to pharmacological treatment, in consultation with healthcare professionals.
Notes : 1Non alcoholic fatty liver diseases, 2Non alcoholic steatohepatitis
Sources: Chris Estes, Homie Razavi, Rohit Loomba, et al. Modeling the Epidemic of Nonalcoholic Fatty Liver Disease Demonstrates an Exponential Increase in Burden of Disease. HEPATOLOGY, VOL. 67, NO. 1, 2018; Zobair M. Younossi, Aaron B. Koenig, Dinan Abdelatif, et al. Global Epidemiology of Nonalcoholic Fatty Liver Disease—Meta-Analytic Assessment of Prevalence, Incidence, and Outcomes. HEPATOLOGY, VOL. 64, NO. 1, 2016; Manuel MSD; World Gastroenterology Organisation; The NASH education program