Responsiveness and minimum important differences for the erection quality scale.
OBJECTIVE
We evaluated the responsiveness and treatment sensitivity of the Erection Quality Scale, and provided further psychometric validation of this scale.


METHODS
An 8-week, placebo controlled, randomized clinical trial investigating the efficacy and safety of vardenafil in patients with erectile dysfunction was performed. The Erection Quality Scale, together with a number of other patient and partner questionnaires, was administered at a screening visit, at baseline, and weeks 4 and 8 of treatment. Erection Quality Scale responsiveness was investigated by evaluating treatment induced changes and modeling using ANCOVA. Internal consistency, convergent and discriminant validity, and minimum important difference of the Erection Quality Scale were also assessed.


RESULTS
Efficacy evaluations demonstrated that the Erection Quality Scale was sufficiently responsive to differentiate the treatment benefits of vardenafil compared with placebo. Internal consistency for the Erection Quality Scale total score was similar across visits, with values high enough to suggest reliability of items included in the scale. Discriminant validity of the Erection Quality Scale total score was demonstrated, with a high correlation with the erectile function domain of the International Index of Erectile Function (0.88, p <0.0001) and negligible correlations with clinical measures assumed to be unrelated to erection quality. All Erection Quality Scale total score comparisons substantially exceeded the 5-point minimum important difference estimate.


CONCLUSIONS
The Erection Quality Scale was responsive and internally consistent, and demonstrated convergent and discriminant validity. Furthermore, this instrument provided a unique contribution to the measurement of erection quality compared to the International Index of Erectile Function. This study provides strong evidence supporting the use of the Erection Quality Scale in clinical trials.
Rosen
Raymond C
RC
Department of Psychiatry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, USA. rrosen@neriscience.com
Wincze
John
J
Mollen
Martin D
MD
Gondek
Kathleen
K
McLeod
Lori D
LD
Fisher
William A
WA
D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D007172:Erectile Dysfunction / Q000188:drug therapy* / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010410:Penile Erection / Q000187:drug effects / Q000502:physiology*; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D010879:Piperazines / Q000008:administration & dosage / Q000627:therapeutic use*; D013450:Sulfones / Q000008:administration & dosage / Q000627:therapeutic use; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014227:Triazines / Q000008:administration & dosage / Q000627:therapeutic use; D000069058:Vardenafil Dihydrochloride
D007093:Imidazoles; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride