The erection hardness score and its relationship to successful sexual intercourse

The Erection Hardness Score (EHS), recently validated, was developed in 1998 as a simple (one-item) method to quantify erection outcome data. Although it is intuitive that erection hardness and successful sexual intercourse (SSI) are related, the link has not been directly established.

To evaluate the relationship between erection hardness (assessed by EHS) and SSI, establishing the EHS as a clinically useful tool.

The data set (N = 307) was from a multinational, double-blind, placebo-controlled trial (with open-label extension) of sildenafil citrate in men with erectile dysfunction.

Event-based modeling used every intercourse attempt and the EHS to estimate the odds ratio of SSI between adjacent EHS categories. Mean-based modeling used mean EHS per patient to determine its relationship to percentage of SSI. Mediation-based modeling used mean EHS and mean percentage of SSI over the double-blind phase to estimate the direct effect of sildenafil treatment on SSI and the indirect effect of sildenafil treatment on SSI via erection hardness.

The odds of SSI for EHS 3 (hard enough for penetration but not completely hard) were 41.9 times (95% confidence interval [CI], 33.0-53.2; P < 0.0001) that for EHS 2 (hard but not hard enough for penetration), and the odds of SSI for EHS 4 (completely hard and fully rigid) were 23.7 times (95% CI, 19.5-28.9; P < 0.0001) that for EHS 3. The percentage of SSI increased approximately curvilinearly with the increase in mean EHS, from almost 60% at EHS 3 to 78.5% at EHS 3.5 and to 93.1% at EHS 4. The indirect effect of sildenafil treatment on SSI via erection hardness accounted for almost 90% of the total effect on SSI (P < 0.0001).

The close and direct relationship between erection hardness and SSI supports the broader use of the EHS-a simple, valid, reliable, and responsive measure-in clinical practice.