Effect of antioxidants on semen parameters in men with oligo‐astheno‐teratozoospermia: a network meta‐analysis

Background: Although antioxidants are largely used in subfertile men with oligo-astheno-teratozoospermia (OAT), the choice among different molecules is challenged by the lack of comparative head-to-head studies. The network meta-analysis (NMA) can overcome limitations of pairwise meta-analyses, since it incorporates direct and indirect evidence into a single model generating an effectiveness hierarchy. Objective: To assess with a NMA the effects of antioxidants in improving seminal parameters in idiopathic OAT. Materials and methods: PubMed, Scopus, Cinahl, and Cochrane Library databases were searched for randomized controlled trials (RCTs) comparing any antioxidant treatment to each other or placebo in men with at least one idiopathic seminal abnormality. Data were included in a random-effects NMA, where efficacy of treatments was ranked by surface under the cumulative ranking curve (SUCRA). Results: 29 RCTs provided information on 2045 men (mean age: 33.5 years) with idiopathic OAT and 19 antioxidant preparations. Compared to placebo, l-carnitine, especially in combination with l-acetyl-carnitine (LAC), had the highest SUCRA for sperm concentration, progressive motility, and morphology. Folate was the only other compound effective on sperm concentration. Vitamin E+selenium or zinc had the highest SUCRA for total motility. A contribution on progressive motility was revealed for pentoxifylline and vitamin E+CoQ10.