Isoflavones versus hormone therapy for reduction of vertebral fracture risk: indirect comparison

Objective: The aim of this study was to conduct an indirect comparison of the results from meta-analyses that evaluated the incidence of osteoporotic vertebral fracture in postmenopausal women exposed to hormone therapy (HT) or isoflavones. Methods: Systematic review and meta-analysis of HT and isoflavones related to the reduction of vertebral fracture risk in osteoporotic women versus the same control (placebo) were undertaken. Then, the combination of the overall results obtained from these two meta-analysis (indirect comparison) was adjusted to the common control (placebo). Results: The indirect odds ratio (OR), obtained from the combination of both individual meta-analyses, was calculated by using the following equation: OR((indirect)) = OR((HT))/OR((isoflav)), with a total indirect variance equivalent to the following equation: var((total)) = var((HT)) + var((isoflav)). These calculations yielded a point estimate of 1.56 (95% CI, 0.39-6.19) for the indirect OR. Conclusions: According to this indirect comparison, there is no statistically significant difference between HT or isoflavones in the reduction of vertebral fracture risk due to osteoporosis, and both interventions seem to be similar for this outcome.