Nonalcoholic fatty liver disease and osteoporosis: a systematic review and meta-analysis

Several major risk factors for osteoporosis have been identified. One of these risk factors is chronic inflammation. Several recent studies have supported the association between low bone mineral density (BMD) and nonalcoholic fatty liver disease (NAFLD), which comprises a spectrum of disorders involving liver inflammation. However, conflicting evidence regarding this association has been obtained thus far. We, therefore, conducted a meta-analysis of observational studies to show the association between NAFLD and BMD. The Cochrane Central Register of Controlled Trials, Cochrane Library, Medline, and Embase were searched from database inception to November 2014 for all observational studies evaluating the association between NAFLD or nonalcoholic steatohepatitis (NASH) and bone mass, BMD, or osteoporosis. All patients were ≥18 years of age and had no other cause of liver disease, osteoporosis, or pathological bone disease at baseline. Risk factors were NAFLD and NASH; control subjects were individuals without NAFLD. Eleven articles underwent full-length review. Data were extracted from five cross-sectional studies involving 1276 participants; 638 had NAFLD. The main meta-analysis showed no significant difference in BMD between patients with fatty liver disease and controls. Among all variables analyzed, body mass index had the strongest and most significant predictive effect on the difference in BMD. Controversy exists regarding the effect of BMD on NAFLD. Further studies are required to fully show this relationship.