The relationship between obesity and the severity of non-alcoholic fatty liver disease: systematic review and meta-analysis

ABSTRACT

Introduction: A number of researches have explored the association between obesity and nonalcoholic fatty liver disease (NAFLD) liver function, histopathology, complications, genetic factors and prognosis, but the results were conflicting and inconclusive.

Areas covered: In this meta-analysis, the liver function, histopathology, metabolic complications, patatin-like phospholipase domain-containing protein 3 (PNPLA3) genetic polymorphism and prognosis were compared between non-obese and obese NAFLD. Pubmed, EMBASE, Cochrane databases were searched to identify eligible studies. The odds ratio (OR) or standardized mean difference (SMD) with 95% confidence intervals (CI) were pooled using fixed- or random-effects models.

Expert commentary: This meta-analysis indicated that for NAFLD patients, obesity (according to ethnic-specific BMI cut-off points to define obesity) could predict a worse long-term prognosis. However, obesity may not be an independent factor for the development of NASH or advanced fibrosis in NAFLD patients and NAFLD should be considered as potential population for pharmacologic treatment regardless of obesity. In addition, PNPLA3 rs738409 may be more relevant to the progression of non-obese NAFLD when compared to obese NAFLD. Importantly, large-sample, long-term follow-up cohort studies based on liver biopsy are highly needed due to limited liver pathology and long-term follow-up data at present.

KEYWORDS:

• Liver disease
• obesity
• metabolic syndrome
• fatty liver
• liver fibrosis

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

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Additional information

Funding

National Natural Science Foundation of China (81570514 and 81500477); Natural Science Foundation of Zhejiang Province (LY15H030017 and LQ15H030006); Public Welfare Science and Technology Project of Wenzhou (Y20150014); Medical Award Fund, Beijing, China (YJHYXKYJJ-162); Scientific and Technological Innovation Team of the Early Warning and Intervention to End-stage Liver Disease of Wenzhou (C20150005); and National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period, China (2013ZX10005002-001-008, 2013ZX10002003 and 2012ZX10002004).