Fatty liver and the metabolic syndrome among Shanghai adults

Abstract

Background and aim: To explore the relationship between fatty liver and the metabolic syndrome in the adults of Shanghai and evaluate the value of fatty liver as a marker for risk factor clustering.

Methods: Questionnaires, physical examinations, laboratory tests (blood lipid and glucose) and real-time liver ultrasonographies were performed in Shanghai adults and analyzed using randomized, multistage, stratified cluster sampling. Prevalence of the metabolic syndrome was defined by the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) criteria with the exception of abdominal obesity (waist circumference > 90 cm in men and > 80 cm in women); fatty liver was diagnosed in accordance with the presence of an ultrasonographic pattern consistent with 'bright' liver (brightness and posterior attenuation of liver).

Results: The study population consisted of 3175 subjects (1218 men) with a mean (+/- SD) age of 52.4 +/- 15.1 years. Metabolic syndrome and fatty liver were found in 726 (22.87%) and 661 (20.82%) of sampled cases, respectively. After adjustment by age and sex, the prevalence of the metabolic syndrome and fatty liver in the general population of Shanghai were 15.30 and 17.29%, respectively. The risk for fatty liver in subjects with abdominal obesity, diabetes, dyslipidemia and hypertension increased 32.78-fold (95% confidence interval (CI) 14.85-72.35), 31.58-fold (95% CI 14.18-70.35), 22.64-fold (95% CI 10.26-49.99) and 23.25-fold (95% CI 10.54-51.30), respectively, compared with controls, whereas the risk for fatty liver in subjects with metabolic syndrome was increased by 39.33-fold (95% CI 17.77-87.05). After the 661 patients with fatty liver had been stratified by body mass index (BMI), the prevalence of abdominal obesity, hypertension and the metabolic syndrome were increased from 25.0, 47.2 and 36.1%, respectively, in people with normal BMI to 81.0, 73.8 and 55.4%, respectively, in obese persons. However, the prevalence of hypertriglyceridemia, high fasting glucose and low high-density lipoprotein-cholesterol showed no significant changes with increased BMI. Moreover, among fatty liver patients with normal BMI, the detection rate for one or more features of metabolic disorders was as high as 83.3% and that for five features was 2.8%. Compared with obesity (BMI > or = 25 kg/m2) and abdominal obesity, fatty liver had the highest clustering rate, specificity, positive predictive value and attributable risk percentage in detecting risk factor clustering in both sexes.

Conclusions: There is a high prevalence of metabolic syndrome and fatty liver among Shanghai adults. Metabolic disorders are closely related to fatty liver; moreover, fatty liver appears to be a good predictor for the clustering of risk factors for metabolic syndrome.