title: Exposure to fluoride in drinking water and hip fracture risk: a meta-analysis of observational studies.
abstract: BACKGROUND
  Many observational studies have shown that exposure to fluoride in drinking water is associated with hip fracture risk. However, the findings are varied or even contradictory. In this work, we performed a meta-analysis to assess the relationship between fluoride exposure and hip fracture risk.
  
  
  METHODS
  PubMed and EMBASE databases were searched to identify relevant observational studies from the time of inception until March 2014 without restrictions. Data from the included studies were extracted and analyzed by two authors. Summary relative risks (RRs) with corresponding 95% confidence intervals (CIs) were pooled using random- or fixed-effects models as appropriate. Sensitivity analyses and meta-regression were conducted to explore possible explanations for heterogeneity. Finally, publication bias was assessed.
  
  
  RESULTS
  Fourteen observational studies involving thirteen cohort studies and one case-control study were included in the meta-analysis. Exposure to fluoride in drinking water does not significantly increase the incidence of hip fracture (RRs, 1.05; 95% CIs, 0.96-1.15). Sensitivity analyses based on adjustment for covariates, effect measure, country, sex, sample size, quality of Newcastle-Ottawa Scale scores, and follow-up period validated the strength of the results. Meta-regression showed that country, gender, quality of Newcastle-Ottawa Scale scores, adjustment for covariates and sample size were not sources of heterogeneity. Little evidence of publication bias was observed.
  
  
  CONCLUSIONS
  The present meta-analysis suggests that chronic fluoride exposure from drinking water does not significantly increase the risk of hip fracture. Given the potential confounding factors and exposure misclassification, further large-scale, high-quality studies are needed to evaluate the association between exposure to fluoride in drinking water and hip fracture risk.
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Xin-Hai
authors.initials: XH
authors.lastname: Yin
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Guang-Lei
authors.initials: GL
authors.lastname: Huang
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Du-Ren
authors.initials: DR
authors.lastname: Lin
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Wan
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Ya-Dong
authors.initials: YD
authors.lastname: Wang
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Ju-Kun
authors.initials: JK
authors.lastname: Song
authors.affiliation: Department of Oral and Maxillary Surgery, Gui Zhou provincial people's hospital, Guiyang, Gui Zhou, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
mesh_terms: D060766:Drinking Water / Q000009:adverse effects*; D005260:Female; D005459:Fluorides / Q000009:adverse effects*; D006620:Hip Fractures / Q000139:chemically induced / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D039781:PubMed; D012307:Risk Factors
chemical_list: D060766:Drinking Water; D005459:Fluorides