Non-alcoholic fatty liver disease among sasang constitutional types: a population-based study in Korea

BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is highly prevalent in populations with metabolic conditions such as obesity and type II diabetes. Specific types of Sasang constitution can act as a risk factor for metabolic diseases, but there are no studies addressing the association between the Sasang constitutional types (SCTs) and NAFLD. METHODS A total of 1184 individuals (508 males, 676 females) that enrolled in the Korean Genome and Epidemiology Study were included in the present study. Classification of SCTs was done with an integrated diagnostic model. NAFLD was diagnosed when the liver attenuation index (LAI) value was <5 Hounsfield units using computed tomography. Relationships between the SCTs and NAFLD were analyzed using multiple logistic regressions. RESULTS The average LAI was 13.3±6.0 in the So-eum (SE) type, 12.3±7.0 in the So-yang (SY) type, and 6.5±9.9 in the Tae-eum (TE) type. Prevalence of NAFLD was 4.7% in the SE type, 14.0% in the SY type, and 34% in the TE type. Even after adjusting for possible confounders, the SY and TE types continued to show a 3.90-fold (95% CI, 1.60-9.51; P=0.0028) and 3.36-fold (95% CI, 1.42-7.92; P=0.0057) increase in chance of having NAFLD, respectively, compared with the SE type. In the additional analysis including only non-obese subjects, the odds ratio of NAFLD was 3.27 (95% CI, 1.29-8.29; P=0.0126) in the SY type and 3.53 (95% CI, 1.30-9.58; P=0.0134) in the TE type compared with SE type. In the multivariate analysis to determine which parameter had an independent association with NAFLD, higher body mass index, alanine aminotransferase (ALT), triglyceride (TG), and low high-density lipoprotein cholesterol were independently associated with developing NAFLD in the SY type. In contrast, male sex, alcohol consumption, higher ALT, TG, and fasting glucose were risk factors for NAFLD in the TE type. CONCLUSIONS These results indicated that the SY and TE types are independent risk factors for NAFLD.