Effect of oestrogen modulation on semen parameters in men with secondary hypogonadism: Systematic review and meta-analysis.

BACKGROUND: Selective oestrogen receptor modulators and aromatase inhibitors stimulate endogenous gonadotrophins and testosterone in men with hypogonadism. There are no systematic reviews/meta-analyses assessing the effects of selective oestrogen receptor modulators/aromatase inhibitors on semen parameters in men with secondary hypogonadism. OBJECTIVES: To assess the effect of monotherapy or a combination of selective oestrogen receptor modulators/aromatase inhibitors on sperm parameters and/or fertility in men with secondary hypogonadism. MATERIALS AND METHODS: A systematic search was conducted in PubMed, MEDLINE, Cochrane Library and ClinicalTrials.gov. Study selection and data extraction were performed by two reviewers independently. Randomised controlled trials and non-randomised studies of interventions reporting effects of selective oestrogen receptor modulators and/or aromatase inhibitors on semen parameters or fertility in men with low testosterone with low/normal gonadotrophins were selected. The risk of bias was assessed using ROB-2 and ROBINS-I tools. The results of randomised controlled trials were summarised using vote counting while summarising effect estimates where available. Non-randomised studies of intervention meta-analysis were conducted using the random-effect model. The certainty of evidence was assessed using GRADE. RESULTS: Five non-randomised studies of interventions (n = 105) of selective oestrogen receptor modulators showed an increase in sperm concentration (pooled mean difference 6.64 million/mL; 95% confidence interval 1.54, 11.74, I2  = 0%) and three non-randomised studies of interventions (n = 83) of selective oestrogen receptor modulators showed an increase in total motile sperm count (pooled mean difference 10.52; 95% confidence interval 1.46-19.59, I2  = 0%), with very low certainty of evidence. The mean body mass index of participants was >30 kg/m2 . Four randomised controlled trials (n = 591) comparing selective oestrogen receptor modulators to placebo showed a heterogeneous effect on sperm concentration. Three included men with overweight or obesity. The results were of very low certainty of evidence. Limited pregnancy or live birth data were available. No studies comparing aromatase inhibitors with placebo or testosterone were found. DISCUSSION AND CONCLUSION: Current studies are of limited size and quality but suggest that selective oestrogen receptor modulators may improve semen parameters in those patients, particularly when associated with obesity.