Background: The decline of testosterone has been known to be associated with the prevalence of erectile dysfunction (ED). But the causal relationship between sex hormones and ED is still uncertain.
Purpose: To prove the association between sex hormones and ED, we carried out a prospective cohort study in a population-based sample.
Methods: A total of 926 men with fixed work units were recruited from the cross-sectional study in 2009 and followed up in 2013. ED was estimated by the score of the five-item international index of erectile dysfunction (IIEF-5). TT, SHBG, E2, FSH, LH were gauged with precise instrument. FT, BT were calculated by Vermeulen’s formula.
Results: A total of 651 Chinese healthy men aged 21-65 were brought into the final sample while 55 men were newly diagnosed as ED. The incidence of ED was 8.45%. Men with the lowest tertile of FT, BT (both RR =4.86, 95% CI: 2.15-10.96) and the highest tertile of FSH (RR =3.91, 95% CI: 1.80-8.51), SHBG (RR =2.67, 95% CI: 1.37-5.18) had a risk of ED. However, these trends were disappeared after adjusting for multiple covariates. In the age group (21-38 years), a decreasing risk of ED was observed with the increase of FT (RR =0.98, 95% CI: 0.96-0.99), BT (RR =0.79, 95% CI: 0.63-0.99). These effects were still statistically significant after controlling for potential confounders including SHBG. TT (RR =0.89, 95% CI: 0.80-0.99) was inversely associated related to ED after further adjusting for SHBG, while SHBG (RR =1.04, 95% CI: 1.02-1.07) remained positively associated with ED after further adjusting for TT. Moreover, SHBG was also a risk factor of ED in middle-aged and elderly men (RR =1.02, 95% CI: 1.01-1.04).
Conclusions: Higher FT and BT levels were associated with a decrease in risk of ED in young men. The inverse association between TT and ED is most likely due to the increase of SHBG. SHBG is an independent risk factor of ED both in young, middle-aged and elderly men.
