Systematic review with meta-analysis: risk factors for non-alcoholic fatty liver disease suggest a shared altered metabolic and cardiovascular profile between lean and obese patients.

BACKGROUND: The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is closely associated with the co-occurrence of multiple pathological conditions characterising the metabolic syndrome (MetS), obesity in particular. However, NAFLD also develops in lean subjects, whose risk factors remain poorly defined.

METHODS: We performed a meta-analysis of 15 studies, along with the data pertaining to our own population (n=336 patients). Data from lean (n=1966) and obese (n=5938) patients with NAFLD were analysed; lean (n=9946) and obese (n=6027) subjects without NAFLD served as controls.

RESULTS: Relative to the lean non-NAFLD controls, lean patients with NAFLD were older (3.79±0.72 years, P=1.36×10-6 ) and exhibited the entire spectrum of the MetS risk factors. Specifically, they had a significant (P=10-10 ) increase in plasma glucose levels (6.44±1.12 mg/dL) and HOMA-IR (0.52±0.094-unit increment), blood lipids (triglycerides: 48.37±3.6, P=10-10 and total cholesterol: 7.04±3.8, mg/dL, P=4.2×10-7 ), systolic (5.64±0.7) and diastolic (3.37±0.9) blood pressure (mm Hg), P=10-10 , and waist circumference (5.88±0.4 cm, P=10-10 ); values denote difference in means±SE. Nevertheless, the overall alterations in the obese group were much more severe when compared to lean subjects, regardless of the presence of NAFLD. Meta-regression suggested that NAFLD is a modifier of the level of blood lipids.

CONCLUSION: Lean and obese patients with NAFLD share a common altered metabolic and cardiovascular profile. The former, while having normal body weight, showed excess of abdominal adipose tissue as well as other MetS features.