Long-term mortality in nonalcoholic fatty liver disease: Is liver histology of any prognostic significance?

Abstract

Over the last decade, a wealth of data has emerged illustrating both the rather benign clinical course of nonalcoholic fatty liver disease (NAFLD) in many individuals, and the unfavorable prognosis of this condition in others. Several studies on long-term mortality of patients suffering from NAFLD confirmed by imaging and/or liver biopsy have been reported. Studies with an average follow-up of at least 5 years are summarized in Table 1 [1-10]. Compared to the general population of same age and sex, NAFLD is associated with a significantly higher overall mortality [1,2,4] and liver-related mortality [1,2]. The long-term prognosis of patients with NAFLD, however, varies across the disease stage. Although the terms simple steatosis and NASH are often used in studies on long-term prognosis to classify patient risk, differing definitions have been used across the studies. Despite that, however, some conclusions can be derived from pooling data from these studies together (Table 1). Within the first 15 years of follow-up, the prevalence of cirrhosis development is significantly higher in patients with NASH as compared to patients with simple steatosis (10.8% vs. 0.7%, respectively, x2 = 23.3, p<0.001). Consequently, the liver-related mortality is also significantly higher in patients with NASH as compared to simple steatosis (7.3% vs. 0.9%, respectively, x2 = 16.7, p<0.001). The overall mortality between these two groups, however, is not significantly different, although there is a trend towards a higher overall mortality in the NASH group (40.5% vs. 32.5%, respectively, x2=3.61, p<0.1).