Association of obesity with bone mineral density and osteoporosis in adults: a systematic review and meta-analysis

Results from previous studies investigating the association of obesity with bone mineral density (BMD) and osteoporosis (OP) are inconsistent. The purpose of the present study was to examine whether obesity is associated with BMD and the risk of OP. This is a meta-analysis. A computerised literature search was conducted using the PubMed, Web of Science, China National Knowledge Internet (CNKI) (Chinese) and Wanfang (Chinese) databases for relevant articles published in English or Chinese before the end of December 2017. Means with standard deviations and odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) were computed to estimate the association between obesity and BMD and the risk of OP by using a random-effects model. In addition, a heterogeneity test and sensitivity analysis were conducted. Adults with obesity had higher BMD than healthy-weight subjects in both the lumbar spine and femoral neck measurement sites. Obesity was positively related to BMD in the two sites, with merged weighted mean difference (WMD) of 0.07 g/cm2 in the lumbar spine (95% CI: 0.045, 0.095; P < 0.001; Pheterogeneity <0.001; I2 = 89.1%) and WMD of 0.087 g/cm2 in the femoral neck (95% CI: 0.063, 0.112; P < 0.001; Pheterogeneity <0.001; I2 = 92.8%). General obesity was negatively related to femoral neck OP, indicating that obesity is a protective factor for OP, with a merged OR of 0.169 (95% CI: 0.132, 0.216; P < 0.001; Pheterogeneity = 0.716; I2 = 0.0%). Adults with obesity had significantly higher BMD than healthy-weight adults. Obesity was positively associated with BMD and negatively correlated with OP.