Sex Hormones Predict the Incidence of Erectile Dysfunction: From a Population-Based Prospective Cohort Study (FAMHES)

Introduction: 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.

Aim: To prove the association between sex hormones and ED, we carried out a prospective cohort study based on our previous cross-sectional study.

Methods: We performed a prospective cohort study of 733 Chinese men who participated in Fangchenggang Area Males Health and Examination Survey from September 2009 to December 2009 and were followed for 4 years. Erectile function was estimated by scores of the five-item International Index of Erectile Dysfunction (IIEF-5) and relative ratios (RRs) were estimated using the Cox proportional hazards regression model.

Main outcome measures: Data were collected at follow-up visit and included sex hormone measurements, IIEF-5 scores, physical examination, and health questionnaires.

Results: Men with the highest tertile of free testosterone (FT) (RR = 0.21, 95% confidence interval [CI]: 0.09-0.46) and the lowest tertile of sex hormone-binding globulin (SHBG) (RR = 0.38, 95% CI: 0.19-0.73) had decreased risk of ED. In young men (aged 21-40), a decreased risk was observed with the increase of FT and bioavailable testosterone (BT) (adjusted RR and 95% CI: 0.78 [0.67-0.92] and 0.75 [0.62-0.95], respectively). Total testosterone (TT) (RR = 0.89, 95% CI: 0.81-0.98) was inversely associated with ED after adjusting for SHBG, while SHBG (RR = 1.04, 95% CI: 1.02-1.06) remained positively associated with ED after further adjusting for TT. Men with both low FT and high SHBG had highest ED risk (adjusted RR = 4.61, 95% CI: 1.33-16.0).

Conclusions: High FT and BT levels independently predicted a decreased risk of ED in young men. Further studies are urgently needed to clarify the molecular mechanisms of testosterone acting on ED.