Obesity Paradox in Chronic Liver Diseases: Product of Bias or a Real Thing?

摘要

In recent years, evidence supporting the theory of obesity paradox has increased, showing that obese/overweight people with prevalent chronic diseases experience lower mortality compared with patients of normal weight. So far, evidence is most comprehensive in cardiovascular and chronic renal diseases; however, published studies are prone to many biases, enabling us to reach a definite conclusion. Available data in chronic liver disease is scarce and ambiguous. Obesity is traditionally associated with nonalcoholic fatty liver disease and steatosis in viral hepatitis and as such one would not expect the obesity paradox to be a real possibility in liver disease. Yet, there seem to be new data indicating the opposite – the obesity paradox exists in severe and end-stage liver cirrhosis, which could be attributed to a better lean mass in patients with higher body mass index, meaning that sarcopenia, as one of the most important prognostic factors of survival, is less likely to be present. Nonetheless, the problem of various methodological problems addressing the association between body weight and mortality, which is present both in liver disease and other chronic diseases, are preventing us from attaining an unanimous conclusion. Still, we should be aware that the obesity paradox might be true, especially in severe and end-stage illness. This suggests focusing our efforts toward preserving or building up fat-free mass and decreasing inflammatory activity responsible for catabolism and sarcopenia, and implying that the underlaying cause should be treated.