Severity of Nonalcoholic Fatty Liver Disease is Associated with Development of Metabolic Syndrome: Results of a 5-Year Cohort Study

Aims: Nonalcoholic fatty liver disease (NAFLD) is considered to be a hepatic manifestation of metabolic syndrome (MS). However, a few studies have examined the effect of NAFLD on the development of MS. We evaluated the relationship between the development of MS and clinical severity of NAFLD according to alanine aminotransferase (ALT) levels. Methods: A retrospective cohort study was conducted. Participants who underwent abdominal ultrasonography and blood samplings for health check-ups both in 2005 and 2010 were recruited. NAFLD was diagnosed if a person showed fatty liver on ultrasonography without significant alcohol consumption. Subjects with MS at baseline were excluded. Results: A total of 2,728 subjects met the inclusion criteria. Fatty liver (FL) with normal ALT was found in 369 (13.5%) subjects and FL with elevated ALT in 328 (12.0%). During 5 years of follow up, 582 (21.3%) incident cases of MS developed between 2005 and 2010. The incidence of MS was higher in patients with NAFLD compared to control group (41.2% in FL with elevated ALT, 34.7% in FL with normal ALT and 15.7% in control, p <0.001). Multivariate analysis showed that odds ratio (OR) and 95% confidence interval (CI) for MS increased according to the severity of NAFLD [OR (95% CI), 1.29 (0.97−1.71) in FL with normal ALT and 1.54 (1.18−1.33) in FL with elevated ALT, p=0.01]. Conclusions: We have demonstrated that development of MS is significantly increased according to the clinical severity of NAFLD. These findings have implications in the clinical availability of NAFLD as a predictor of MS.