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.
BACKGROUND
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.


OBJECTIVE
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.


METHODS
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
James W
JW
Department of Pharmacy Administration, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, USA. jwshaw@uic.edu
Reardon
Gregory
G
Sandor
David W
DW
Rosen
Raymond C
RC
Ferguson
David M
DM
D007172:Erectile Dysfunction / Q000175:diagnosis* / Q000188:drug therapy*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology* / Q000627:therapeutic use*; D007391:International Cooperation; D007398:Interpersonal Relations; D008297:Male; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use*; D010879:Piperazines / Q000494:pharmacology* / Q000627:therapeutic use*; D012016:Reference Values; D012720:Severity of Illness Index; D012725:Sexual Behavior; D013450:Sulfones / Q000494:pharmacology / Q000627:therapeutic use; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D014227:Triazines / Q000494:pharmacology / Q000627:therapeutic use; D000069058:Vardenafil Dihydrochloride
D007093:Imidazoles; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride