Body mass index and the risk of low bone mass-related fractures in women compared with men: A PRISMA-compliant meta-analysis of prospective cohort studies.
BACKGROUND
Body mass index (BMI) is inconsistently associated with the progression of low bone mass-related fractures. We conducted a systematic review and meta-analysis to summarize the evidence regarding the relationship between BMI and the risk of fracture in men and women separately. Furthermore, we analyzed the association between BMI and fracture risk in women compared with men.


METHODS
PubMed, EmBase, and the Cochrane Library were searched up to November 2015 to identify prospective cohort studies of low bone mass-related fractures. Prospective cohort studies that reported effect estimates of fracture risk for different BMI categories compared to normal weight were included. Relative risk (RR) and the ratio of relative risk (RRR) were calculated using a random-effect model to measure the relationship between BMI and fracture risk.


RESULTS
We analyzed 37 cohorts (32 articles), which included a total of 506,004 women and 118,372 men; overall, 38,200 incident cases were reported. Overall, a lower BMI was not associated with fracture risk in men (RR: 1.50, 95% confidence interval [CI]: 1.00-2.26; P = 0.051) or women (RR: 1.25, 95% CI: 0.97-1.62; P = 0.083). Although a higher BMI might play a beneficial impact in men (RR: 0.80, 95% CI: 0.69-0.93; P = 0.003), it has little effect in women (RR: 0.91, 95% CI: 0.74-1.11; P = 0.343). In addition, an increase in BMI by 5 kg/m decreased the risk of fractures in men (RR: 0.90, 95% CI: 0.83-0.98; P = 0.017) and women (RR: 0.85, 95% CI: 0.81-0.89; P < 0.001). Finally, there was no evidence of a sex difference in the RR for fractures between participants with different BMI categories compared with those with normal BMI. Finally, gender did not affect the risk of fracture for any category of BMI values.


CONCLUSIONS
Higher BMI may affect the risk of fractures regardless of the sex. This association may be due to the interaction between the participants' BMI and their bone mass density.
Department of Orthopaedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing Department of Respiratory Medicine, Three Affiliated Hospital of Zunyi Medical College, Guizhou, China.
Bing-Yan
BY
Xiang
Wei
W
Huang
Guo-Qi
GQ
Zhou
Ning
N
Hu
Hong
H
Chen
Cheng
C
Chen
D000367:Age Factors; D015992:Body Mass Index; D015519:Bone Density; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000473:pathology; D006801:Humans; D008297:Male; D050177:Overweight / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013851:Thinness / Q000453:epidemiology