Raloxifene Lowers Plasma Lipoprotein(a) Concentrations: a Systematic Review and Meta-analysis of Randomized Placebo-Controlled Trials

BACKGROUND AND AIMS: Lipoprotein(a) (Lp(a)) is a proatherogenic plasma lipoprotein and an independent risk factor for atherosclerotic cardiovascular disease. We investigated the effects of raloxifene, selective estrogen receptor modulator, on circulating Lp(a) levels in postmenopausal women using a systematic review and meta-analysis of randomized controlled trials (RCTs). METHODS: To identify relevant studies, electronic databases (PUBMED, Scopus, Web of Science, and Google Scholar) were searched by up to May 2015 to find controlled trials exploring the effects of oral raloxifene treatment on plasma Lp(a) levels in postmenopausal women. A random-effects model and generic inverse variance method were used for quantitative data synthesis. RESULTS: Overall, seven eligible RCTs with ten treatment arms were included in this meta-analysis. Meta-analysis suggested a significant reduction of Lp(a) levels after treatment with raloxifene (standardized mean difference (SMD) -0.42; 95% CI -0.65, -0.19; p < 0.001), which may be considered as a medium effect size. When the studies were categorized according to the administered dose, there was a significant effect in both subsets of studies with administered doses ≤60 mg/day (SMD -0.43; 95% CI -0.73, -0.13; p = 0.004) and >60 mg/day (SMD -0.36; 95% CI -0.68, -0.05; p = 0.025). No significant association between the changes in plasma concentrations of Lp(a) with dose and baseline Lp(a) levels was found in the random-effects meta-regression analysis. However, a significant inverse association was observed between the Lp(a)-lowering effect of raloxifene and duration of treatment (p = 0.001). CONCLUSIONS: Results of the present meta-analysis showed a reduction in plasma Lp(a) concentrations of postmenopausal women with oral raloxifene treatment.