Meta-Analysis
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Feb 7, 2015; 21(5): 1650-1662
Published online Feb 7, 2015. doi: 10.3748/wjg.v21.i5.1650
Central obesity and nonalcoholic fatty liver disease risk after adjusting for body mass index
Qing Pang, Jing-Yao Zhang, Si-Dong Song, Kai Qu, Xin-Sen Xu, Su-Shun Liu, Chang Liu
Qing Pang, Jing-Yao Zhang, Si-Dong Song, Kai Qu, Xin-Sen Xu, Su-Shun Liu, Chang Liu, Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
Author contributions: Pang Q and Zhang JY contributed equally to this work; Pang Q participated in the research design, writing of the paper, and literature searches; Zhang JY participated in writing of the paper, literature searches, and data analysis; Song SD and Qu K participated in critical revision of the paper, and extraction and analysis of data; Xu XS and Liu SS participated in revision of the paper, and final approval; Liu C participated in the research conception and design.
Supported by National Natural Science Foundation of China, No. 30872482 and No. 81072051.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Chang Liu, MD, PhD, Professor, Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi’an Jiaotong University, No. 277 West Yan-ta Road, Xi’an 710061, Shaanxi Province, China. liuchangdoctor@163.com
Telephone: +86-29-82653900 Fax: +86-29-82653905
Received: May 10, 2014
Peer-review started: May 10, 2014
First decision: May 29, 2014
Revised: June 11, 2014
Accepted: August 28, 2014
Article in press: August 28, 2014
Published online: February 7, 2015
Abstract

AIM: To investigate whether central obesity is associated with nonalcoholic fatty liver disease (NAFLD) formation after adjusting for general obesity.

METHODS: The online databases PubMed, EMBASE, and ISI Web of Science were searched for studies estimating the influence of central obesity on NAFLD occurrence published through April 2014. Studies that did not adjust for body mass index (BMI) were excluded. In addition, the independent effect of BMI was also assessed with the included studies. The pooled effect sizes and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models based on the degree of heterogeneity. Furthermore, subgroup analyses, meta-regression, sensitivity analyses, and publication bias were performed.

RESULTS: Twenty eligible studies were identified. The summary odds ratio (OR) values per-unit increase in waist circumference (WC) and BMI for NAFLD formation were 1.07 (95%CI: 1.03-1.10, I2 = 73.9%, n = 11 studies) and 1.25 (95%CI: 1.13-1.38, I2 = 88.7%, n = 11 studies), respectively. When the indices were expressed as binary variables (with the non-obesity group as reference), the pooled OR in WC, waist-to-hip ratio, and BMI were 2.34 (95%CI: 1.83-3.00, I2 = 41.8%, n = 7 studies), 4.06 (95%CI: 1.53-10.79, I2 = 65.7%, n = 3 studies), and 2.85 (95%CI: 1.60-5.08, I2 = 57.8%, n = 5 studies), respectively. Using the same studies as the latter (n = 5), pooled OR in WC was 3.14 (95%CI: 2.07-4.77), which is greater than that in BMI.

CONCLUSION: Central obesity may pose a greater threat to national health than general obesity, although both are independently associated with increased risk of NAFLD.

Keywords: Central obesity, General obesity, Nonalcoholic fatty liver disease, Body mass index, Waist circumference

Core tip: Central and general obesity are independently associated with increased risk of nonalcoholic fatty liver disease (NAFLD). Per-unit increase in waist circumference and body mass index increased the incidence risk of NAFLD by 0.07- and 0.25-fold, respectively. The risk for disease is increased in individuals with a higher waist circumference, waist-to-hip ratio, and body mass index by 1.34-, 3.06-, and 1.85-fold, respectively. The results of this analysis suggest that central obesity poses a greater threat to national health than general obesity. Therefore, future studies should place a greater emphasis on central obesity.