Effect of statin treatment on homocysteine concentrations: an updated systematic review and meta-analysis with meta-regression

Background and aims: Statins might exert atheroprotective effects through lowering the pro-atherogenic amino acid homocysteine. We addressed this issue by conducting an updated systematic review and meta-analysis of the effect of statins on circulating homocysteine. Methods: A systematic literature search was conducted in PubMed, Web of Science, and Scopus, from inception to July 2021. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for analytical studies. Certainty of evidence was assessed using GRADE. Results: In 61 treatment arms in 2,218 patients (mean age 55 years, 52% males), statins significantly reduced homocysteine concentrations (weighted mean difference, WMD=-2.46 µmol/L, 95% CI -3.17 to -1.75 µmol/L, p<0.001; high certainty of evidence). Similar results were observed in a subgroup of 10 randomized placebo-controlled studies (WMD=-2.45 µmol/L, 95% CI -4.43 to -0.47 µmol/L, p=0.015). The extreme heterogeneity observed was virtually removed in a subgroup of 10 studies using fluorescence polarization immunoassay for homocysteine measurement. There was no publication bias. In sensitivity analysis, the pooled WMD values were not modified when individual studies were sequentially removed. In meta-regression, the WMD was significantly associated with proportion of males and publication year. Conclusions: Statins significantly lower homocysteine concentrations (PROSPERO registration number: CRD42021273963).