Fluoride for treating postmenopausal osteoporosis

Abstract

Background: Osteoporosis is a condition that results in an increased risk of fractures due to the reduction of bone volume, which is caused by an imbalance between bone formation and bone resorption. Because of this property, fluoride has been used for over 30 years as a treatment for osteoporosis. Objectives: To assess the efficacy of fluoride therapy on bone loss, vertebral and non-vertebral fractures and side effects in postmenopausal women. Search methods: We searched MEDLINE, Current Contents and the Cochrane Controlled Trial Registry up to December 1998. Selection criteria: Two independent reviewers selected RCTs which met predetermined inclusion criteria. Data collection and analysis: Two reviewers independently extracted data using predetermined forms and assessed the methodological quality of the trials using a validated scale. For dichotomous outcomes, relative risks (RR) were calculated and for continuous outcomes, weighted mean differences (WMD) of percentage change from baseline were calculated. Where heterogeneity existed (determined by a chi-square test) a random effects model was used. Main results: 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 two years of treatment and 16.1%(95%CI: 14.65,17.5) after four years. The RR for new vertebral fractures was not significant at two years [0.87 (95%CI: 0.51,1.46)] or at four years [0.9(95%CI: 0.71,1.14)]. The RR for new non-vertebral fractures was not significant at two years 1.2(95%CI: 0.68,2.1) but was increased at four years in the treated group 1.85(95%CI: 1.36,2.5), especially if used at high doses and in a non slow release form. The RR for gastrointestinal side effects was not significant at two years 2.18(95%CI: 0.86,1.21) but was increased at four 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. There is no evidence of an important difference in the number of withdrawals and dropouts between treated and control groups at two and four years. Authors' conclusions: Although fluoride has an ability to increase BMD at lumbar spine, it does not result in a reduction of vertebral fractures. In increasing the dose of fluoride, one increases the risk of non-vertebral fracture and gastrointestinal side effects without any effect on the vertebral fracture rate.