Association between nonalcoholic fatty liver disease and carotid intima-media thickness according to the presence of metabolic syndrome

Objective: Controversy exists as to whether the association between nonalcoholic fatty liver disease (NAFLD) and atherosclerosis is independent of other metabolic disorders. We examined the association between NAFLD and carotid intima-media thickness (IMT) according to the presence of metabolic syndrome (MetS). Methods: A cross-sectional analysis was performed among 556 men and 465 women, ages 30-79 years. The presence of NAFLD was evaluated ultrasonographically. Carotid IMT was determined ultrasonographically by the average of the maximal IMT at each common carotid artery. Independent associations between NAFLD and IMT were assessed using multiple linear and logistic regression models, after adjusting for age, sex, waist circumference, systolic blood pressure, fasting glucose, total/HDL-cholesterol ratio, smoking, and alcohol consumption. Results: After adjusting for major risk factors, subjects with NAFLD had greater carotid IMT than subjects without NAFLD (difference 0.034 mm, p = 0.016). However, the difference in IMT was significant only in subjects with MetS (0.060 mm, p = 0.015) and not in subjects without MetS (0.015 mm, p = 0.384). Similarly, the NAFLD-associated adjusted odds ratio for increased IMT, defined as the sex-specific top quintile, was 1.63 (95% CI, 1.10-2.42) in all subjects and 2.08 (95% CI, 1.19-3.66) in subjects with MetS, but 1.18 (95% CI, 0.64-2.19) in subjects without MetS. When the analysis was performed according to the number of metabolic abnormalities, the NAFLD-IMT association was observed only in subjects with four or more abnormalities. Conclusion: These results suggest that NAFLD is independently associated with carotid atherosclerosis only in people who have multiple metabolic abnormalities.