NAFLD, NASH Linked To Metabolic Syndrome And Cardiovascular Disease
Study of the Liver (EASL) further confirms that nonalcoholic fatty liver disease (NAFLD) and its most severe form, nonalcoholic steatohepatitis (NASH), are associated with the metabolic syndrome and pose an increased risk of cardiovascular disease.
NAFLD and NASH are significant health problems that affect millions of people worldwide, especially in Western countries. NAFLD is a fatty accumulation in the liver that does not result from excessive use of alcohol. When this condition progresses, and is associated with inflammation and liver damage, it is then called NASH, which is thought to occur in 15% to 25% of cases of NAFLD. NASH is clearly associated with the risk of developing liver cirrhosis, and its complications, including hepatocellular carcinoma, the most frequent primary tumour of the liver. NASH-related cirrhosis is an increasingly occurring indication for liver transplantation.
In turn, the metabolic syndrome is a combination of risk factors, including high blood lipids, abdominal obesity, and a tendency to diabetes. The association between NAFLD, NASH, and the metabolic syndrome is a great cause for concern because people with the metabolic syndrome are at increased risk for type 2 diabetes and cardiovascular disease, including heart attack and stroke.
According to Dr. Fabio Marra, Associate Professor of Medicine at the University of Florence, "When I see a patient with a fatty liver, I have to consider all the other risk factors for cardiovascular diseases and try to intervene aggressively to limit the effects of those other factors, because accumulating data indicate that the fatty liver may be itself an additional risk factor."
The precise prevalence of NAFLD and NASH within individual countries is elusive. Large scale epidemiological studies are still needed, and definitive laboratory tests to identify patients with NASH are unavailable. At present, a biopsy of the liver is the only accepted diagnostic method. Despite these limitations, the best current estimates suggest that in the general population NAFLD can be found in one-fourth to one-third of adults in Western countries. One U.S. study of children who died as a result of accidents found that 13% had NAFLD.
While a number of risk factors have been identified, the foregoing percentages rise most dramatically among people who are obese. For example, studies have found NAFLD in 84% to 96% of patients undergoing bariatric surgery. For these reasons, NAFLD and NASH are seen to be increasing as poor dietary habits and sedentary lifestyles become more widespread.
Although NAFLD and NASH have not to date been included as components of the metabolic syndrome, increasingly the onset of NAFLD is being viewed by experts as an early event in the development of insulin resistance and therefore as an indicator or predictor of future metabolic syndrome.
Among key unanswered questions: Why do some people with NAFLD live out their lives unaffected by their condition of having a fatty liver, while others go on to develop NASH and cirrhosis, or diabetes and/or cardiovascular disease?
At present, there are no specific therapies for NASH. Among the chief recommendations offered to patients are to lose weight gradually (particularly if one is obese) and to increase physical activity, to eat a healthy diet, and to avoid alcohol.