Stopwatch-assessed duration of erection: a new measure of the efficacy of erectile dysfunction treatments

Results are reported from the first two adequate trials of the PDE-5 inhibitor vardenafil using a stopwatch to precisely measure erection duration in men with ED. Two randomized, multicenter, double-blind, placebo-controlled trials were conducted: a crossover 4-week treatment in men with ED (ENDURANCE) and a parallel group, 12-week treatment in men with ED and dyslipidemia (the dyslipidemia study). Stopwatch-assessed duration of erection leading to successful intercourse measured by Sexual Encounter Profile question-3 (SEP-3) was the primary end point in ENDURANCE and one of the secondary end points in the dyslipidemia study. Other efficacy end points included responses to SEP-2, SEP-3 and International Index of Erectile Function-Erectile Function (IIEF-EF) domain scores. Adverse events were recorded. Duration of erection (least squares mean ± s.e.) leading to successful intercourse was statistically superior in men receiving vardenafil versus placebo (12.8 ± 1.0 versus 5.5 ± 1.0 min; p<0.001 in ENDURANCE and 10.0 ± 0.8 versus 3.4 ± 0.8; p<0.001 in the dyslipidemia study), with a difference of 7.4 and 6.6 min, respectively, between treatment groups. Results for SEP-2, SEP-3 and IIEF-EF domain scores were consistent across studies and with stopwatch-assessed measures for duration of erection. Vardenafil was well tolerated. Duration of erection leading to successful intercourse is an important indicator of the efficacy of ED treatment. The stopwatch approach offers an alternative, precise and reproducible measure of efficacy. We propose this approach as a potential new paradigm for assessing the efficacy of ED treatments.