Fluoride for the treatment of postmenopausal osteoporotic fractures: a meta-analysis

We conducted an effectiveness meta-analysis to determine the efficacy of fluoride therapy on bone loss, vertebral and nonvertebral fractures and side effects in postmenopausal women. A literature search was conducted on MEDLINE, Current Contents and the Cochrane Controlled Trial Registry. Two independent reviewers selected randomized controlled trials which met predetermined inclusion criteria. They independently extracted data using predetermined forms and assessed the methodologic quality of the trials using a validated scale. For dichotomous outcomes, the relative risk (RR) was calculated, and for continuous outcomes, the weighted mean difference (WMD) of percentage change from baseline was calculated. Where heterogeneity existed (determined by a chi-square test) a random effects model was used. Eleven studies (1429 subjects) met the inclusion criteria. The increase in lumbar spine bone mineral density (BMD) was found to be higher in the treatment group than in the control group with a WMD 8.1% (95% CI: 7.15, 9.09) after 2 years of treatment and 16.1% (95% CI: 14.65, 17.5) after 4 years. The RR for new vertebral fractures was not significant at 2 years [0.87 (95% CI: 0.51, 1.46)] or at 4 years [0.9 (95% CI: 0.71, 1.14)]. The RR for new nonvertebral fractures was not significant at 2 years [1.2 (95% CI: 0.68, 2.10)] but was increased at 4 years in the treated group [1.85 (95% CI: 1.36, 2.50)], especially if used at high doses and in a non-slow-release form. The RR for gastrointestinal side effects was not significant at 2 years [2.18 (95% CI: 0.86, 1.21)] but was increased at 4 years in the treated group [2.18 (95% CI: 1.69, 4.57)], especially if fluoride was used at high doses and in a non-slow-release form. The number of withdrawals and dropouts was not different between treated and control groups at 2 and 4 years. Thus, although fluoride has an ability to increase bone mineral density at the lumbar spine, it does not result in a reduction in vertebral fractures. Increasing the dose of fluoride increases the risk of nonvertebral fractures and gastrointestinal side effects without any effect on the vertebral fracture rate.