Cigarette smoking and risk of hip fracture in women: A meta-analysis of prospective cohort studies

Background and objectives Whether cigarette smoking can increase the risk of hip fracture in women is unclear. This meta-analysis, which pooled results from 10 prospective cohort studies, was performed to derive a more precise estimation between cigarette smoking and the risk of hip fracture in women. Materials and methods Pubmed, Cochrane Central Register of Controlled Trials and ISI Web of Science were systematically searched to identify relevant studies. A meta-analysis was performed to examine the association among 10 studies. The pooled risk estimates were calculated by using both random- and fixed-effects model. Heterogeneity among articles and their publications bias were also tested. All of the statistical analyses were performed using the software programs STATA (version 12.0). Results Relative risk was significantly increased in current female smokers (pooled RR, 1.30; 95%CI, 1.16–1.45). The association was significant among the high-dose smokers (more than 15 cigarettes per day) while not among the low-does smokers (less than 15 cigarettes per day). Omission of any single study had little effect on the pooled risk estimate. Former smokers had a similar RR of hip fracture (RR, 1.02; 95%CI, 0.93–1.11) to published papers. Smoking cessation for ≥10 years leads to a significant decline in risk. Conclusions Smoking is associated with an increased hip fracture risk in women. Cessation of smoking for ≥10 years had a decreased impact on risk of hip fracture. Given the inconsistency among the studies in the choice of adjustments, the associations between cigarette smoking and risk of hip fracture in women await further investigation.