Obesity is an independent risk factor for non-alcoholic fatty liver disease: evidence from a meta-analysis of 21 cohort studies

BackgroundThe association between obesity and nonalcoholic fatty liver disease (NAFLD) has not been fully quantified, and the magnitude of NAFLD risk associated with obesity is still unclear. A meta-analysis of cohort studies was performed to elucidate the NAFLD risk associated with obesity. MethodsPubmed, Web of Science and Embase were searched for cohort studies assessing NAFLD risk associated with obesity or increased body mass index (BMI). Relative risks (RRs) with 95% confidence intervals (95%CIs) were pooled using random-effects model of meta-analysis. ResultsTwenty-one cohort studies including 13 prospective studies and 8 retrospective studies were finally included. There were a total of 381,655 participants in the meta-analysis. Compared with normal weight, obesity independently led to a 3.5-fold increased risk of developing NAFLD (RR=3.53, 95%CI 2.48 to 5.03, P<0.001). Meta-analysis also suggested an obvious dose-dependent relationship between BMI and NAFLD risk (per 1-unit increment in BMI: RR=1.20, 95%CI 1.14 to 1.26, P<0.001). Subgroup analyses further identified the robustness of the association above. No obvious risk of publication bias was observed. ConclusionObese individuals have a 3.5-fold increased risk of developing NAFLD, and there is an obvious dose-dependent relationship between BMI and NAFLD risk. (c) 2016 World Obesity