Combination clomiphene citrate and anastrozole duotherapy improves semen parameters in a multi-institutional, retrospective cohort of infertile men.

In men with impaired semen parameters, empiric medical therapies such as clomiphene citrate, a selective estrogen receptor modulator (SERM), and anastrozole, a selective aromatase inhibitor, are often employed. The effects of jointly administering these agents on semen parameters are not well understood. Here, we describe the findings of our multi-center, retrospective cohort study of men with idiopathic primary or secondary infertility. Twenty-one men were treated with combination therapy (anastrozole and clomiphene) and 69 men were treated with monotherapy (anastrozole). Patients with pre-treatment normozoospermia and recent or current exogenous testosterone therapy were excluded. Baseline and post-treatment semen and sex hormone parameters were compared among groups. The median follow-up duration was 91 days [interquartile range (IQR), 64-117 days]. Following treatment, 43% of men in the combination therapy group demonstrated normozoospermia, compared to 25% in the monotherapy group. Furthermore, men in the combined group demonstrated marked improvements in total motile sperm count (TMSC) [11.3 2.1 million (M), P=0.03]. There were no significant differences in hormone levels among the two groups following treatment. Combination therapy with clomiphene citrate and anastrozole was associated with modest benefits in post-treatment semen parameters, when compared to anastrozole monotherapy. These benefits may contribute to improvements in pregnancy outcomes with less invasive assisted reproductive technologies, such as intrauterine insemination (IUI). Future investigations with larger sample sizes and prospective study designs are necessary.