Table 2. Summary of the evidence demonstrating the association between late-onset hypogonadism and sexual dysfunction.

Reference	Study type	Results
Boloña et al. 37	Systematic review and meta-analysis of 17 RCTs	In hypogonadal men Testosterone treatment caused a large effect on libido (pooled effect size 1.31, 95% confidence interval 0.40–2.25).
Isidori et al. 38	Meta-analysis of 17 randomised placebo- controlled trials	Meta-analysis showed that in men with an average baseline testosterone level below 12 nmol/L, testosterone treatment moderately improved the number of nocturnal erections, sexual thoughts and motivation, number of successful intercourses, scores of erectile function, and overall sexual satisfaction. However, meta-regression analysis showed that the effects of testosterone supplementation on erectile function, but not libido, were inversely related to the mean baseline testosterone concentration.
Jain et al. 43	Meta-analysis of 16 studies (five RCTs)	In five RCTs, erectile function response to TRT was 65.4% versus 16.7% ( P <0.001).
Tsertsvadze et al. 42	Meta-analysis of 15 RCTs	Inconsistent data. Results for most trials suggested that TRT was no different from placebo.
Corona et al. 39	Meta-analysis of 41 RCTs	Forty-one studies were included and supplementary testosterone improved both spontaneous and sex-related erections as well as libido in hypogonadal patients.
Corona et al. 40	Meta-analysis of 14 RCTs	TRT induced a significant improvement of the erectile function score component compared with placebo ( P <0.0001).

RCT, randomised controlled trial; TRT, testosterone replacement therapy.