Effect of extended-release niacin on plasma Lipoprotein(a) levels: a systematic review and meta-analysis of randomized placebo-controlled trials.

AIM: Lipoprotein(a) (Lp(a)) is a proatherogenic and prothrombotic lipoprotein. Our aim was to quantify the extended-release nicotinic acid Lp(a) reducing effect with a meta-analysis of the available randomized clinical trials. METHODS: A meta-analysis and random-effects meta-regression were performed on data pooled from 14 randomized placebo-controlled clinical trials published between 1998 and 2015, comprising 17 treatment arms, which included 9013 subjects, with 5362 in the niacin arm. RESULTS: The impact of ER niacin on plasma Lp(a) concentrations was reported in 17 treatment arms. Meta-analysis suggested a significant reduction of Lp(a) levels following ER niacin treatment (weighted mean difference - WMD: -22.90%, 95% CI: -27.32, -18.48, p<0.001). Results also remained similar when the meta-analysis was repeated with standardized mean difference as summary statistic (WMD: -0.66, 95% CI: -0.82, -0.50, p<0.001). When the studies were categorized according to the administered dose, there was a comparable effect between the subsets of studies with administered doses of <2000mg/day (WMD: -21.85%, 95% CI: -30.61, -13.10, p<0.001) and ≥2000mg/day (WMD: -23.21%, 95% CI: -28.41, -18.01, p<0.001). The results of the random-effects meta-regression did not suggest any significant association between the changes in plasma concentrations of Lp(a) with dose (slope: -0.0001; 95% CI: -0.01, 0.01; p=0.983), treatment duration (slope: -0.40; 95% CI: -0.97, 0.17; p=0.166), and percentage change in plasma HDL-C concentrations (slope: 0.44; 95% CI: -0.48, 1.36; p=0.350). CONCLUSION: In this meta-analysis of randomized placebo-controlled clinical trials, treatment with nicotinic acid was associated with a significant reduction in Lp(a) levels.