Validation of Stopwatch Measurements of Erection Duration against Responses to the Sexual Encounter Profile and International Index of Erectile Function in Patients Treated with a Phosphodiesterase Type 5 Inhibitor
Article first published online: 26 JAN 2010
© 2010 International Society for Sexual Medicine
The Journal of Sexual Medicine
Volume 7, Issue 3, pages 1147–1159, March 2010
How to Cite
Shaw, J. W., Reardon, G., Sandor, D. W., Rosen, R. C. and Ferguson, D. M. (2010), Validation of Stopwatch Measurements of Erection Duration against Responses to the Sexual Encounter Profile and International Index of Erectile Function in Patients Treated with a Phosphodiesterase Type 5 Inhibitor. Journal of Sexual Medicine, 7: 1147–1159. doi: 10.1111/j.1743-6109.2009.01643.x
- Issue published online: 1 MAR 2010
- Article first published online: 26 JAN 2010
- Erectile Dysfunction;
- Duration of Erection;
Introduction. Although the Sexual Encounter Profile (SEP) and International Index of Erectile Function (IIEF) are frequently used to measure erectile dysfunction (ED) treatment outcomes, stopwatch-assessed duration of erection is a new, objective, and potentially useful endpoint of ED treatment effect.
Aims. To assess the validity and reliability of stopwatch-assessed erection duration against responses to SEP items 2 (SEP-2) and 3 (SEP-3) and IIEF scale scores.
Methods. Data were taken from a multi-center trial of vardenafil for the treatment of ED. Patients were randomized to vardenafil 10 mg or placebo for 4 weeks. After a 1-week washout period, patients received the alternate therapy for an additional 4 weeks. An electronic diary was used to record information about sexual attempts. The duration of erection was measured using a stopwatch and transcribed into the diary. The SEP was completed following each sexual attempt, and the IIEF was completed at the end of each treatment period.
Main Outcome Measures. Mean and median values of erection duration, mean SEP-2 and SEP-3 success rates, and scores for each of the 5 IIEF scales were calculated.
Results. At baseline, correlations of median erection duration with the 5 IIEF scale scores ranged from 0.06 to 0.53, while correlations with mean SEP-2 and SEP-3 success rates were 0.66 and 0.49, respectively. Compared with the other measures, mean and median values of erection duration were less sensitive to differences between placebo- and vardenafil-treated patients and less responsive to clinical change associated with treatment crossover. However, mean erection duration exhibited a good level of reliability (intraclass correlation coefficient = 0.72, P < 0.001).
Conclusions. This study provides evidence for the validity and reliability of stopwatch-assessed duration of erection. Our findings suggest that erection duration is suitable for use as a unique endpoint in ED treatment-efficacy trials conducted for phosphodiesterase type 5 inhibitors. Shaw JW, Reardon G, Sandor DW, Rosen RC, and Ferguson DM. Validation of stopwatch measurements of erection duration against responses to the Sexual Encounter Profile and International Index of Erectile Function in patients treated with a phosphodiesterase type 5 inhibitor. J Sex Med 2010;7:1147–1159.