The association between overweight/obesity and vertebral fractures in older adults: a meta-analysis of observational studies.

A meta-analysis of observational studies was conducted to assess the relationship between overweight/obesity and vertebral fractures in older adults. We found that overweight was related to a decreased risk of vertebral fractures in female and non-Asian populations, while obesity failed to be associated with vertebral fracture risks based on the present data. INTRODUCTION Recent investigations suggest that the influence of overweight/obesity on fracture risks is site-specific, while conflicting data were reported related to vertebral fracture. This meta-analysis was performed to qualitatively assess the relationship between overweight/obesity and the risk of vertebral fracture. METHODS MEDLINE, Web of Science, Embase, and Cochrane were searched for relevant observational articles assessing the vertebral fracture risk of the overweight or obese population compared to normal population. Two independent reviewers conducted data extraction and quality assessment. Relative risks (RR) and 95% confidence intervals (CI) were pooled using a random effect model. RESULTS Eleven studies including 1,078,094 participants were extracted from 1645 records. Pooled RR showed that decreased risk of vertebral fractures was observed in the overweight older adults (RR: 1.16; 95% CI: 1.07-1.26; I2: 51.8%), but not in the obese populations (RR: 0.98; 95% CI: 0.82-1.17; I2: 92.1%). In the subgroup analysis, we found a significant inverse association between overweight and risk of vertebral fracture in women (RR: 0.92; 95% CI: 0.85-1.00; I2: 0.0%), non-Asian areas (RR: 0.89; 95% CI: 0.80-0.99; I2: 40.7%), sample size > 2000 (RR: 0.87; 95% CI: 0.80-0.94; I2: 4.9%), and quality score > 7 (RR: 0.87; 95% CI: 0.79-0.95; I2: 21.9%). Furthermore, pooled studies of sample size > 2000 (RR: 0.66; 95% CI: 0.76, 0.89; I2: 52.1%) and quality score > 7 (RR: 0.75; 95% CI: 0.62, 0.91; I2: 68.1%) showed that the people with obesity had a significantly lower prevalence of vertebral fracture. CONCLUSIONS Overweight aged adults tend to have a lower vertebral fracture risk. When gender and ethnicity were taken into consideration, the inverse relationship between overweight and vertebral fracture risk were only observed in female and non-Asian populations. Besides, there is insufficient data to conclude the relationship between obesity and the risk of vertebral fractures, and thus, further studies are needed.