Responsiveness of the Peyronie’s Disease Questionnaire (PDQ)
Karin S. Coyne PhD, MPH; Brooke M. Currie MPH; Christine L. Thompson BS; and Ted M. Smith PhD
ONLINE: February 9, 2015 – The Journal of Sexual Medicine
Because Peyronie’s disease (PD) can lead to psychological issues and great distress for men, a patient-reported outcome (PRO) measure that includes patient perspectives is necessary. Such an instrument would also be in line with recommendations from the Standards for Clinical Trials in Male Sexual Dysfunction.
The Peyronie’s Disease Questionnaire (PDQ) is a self-administered PRO that measures psychosexual consequences and treatment outcomes of PD. The PDQ is intended for men who have had vaginal intercourse in the past 3 months and includes three subscales:
1. Peyronie’s Psychological and Physical Symptoms (6 items, based on patient’s most recent sexual experience)
2. Peyronie’s Symptom Bother (6 items, based on patient’s most recent sexual experience)
3. Penile Pain (3 items)
This study examined the responsiveness of the PDQ. The authors define responsiveness in this way:
“the extent to which the instrument accurately reflects change in a patient’s condition – in other words, responsiveness is the ability of an instrument to discriminate between patients who improve in health status and those who do not.”
Without adequate responsiveness, a PRO might not accurately show statistical and clinical significance.
Two trials of collagenase clostridium histolyticum in men with PD were used (IMPRESS I and II). Each trial lasted for 52 weeks and was multicenter, double-blind, randomized, and placebo-controlled.
The trials were identical in design and included PD men with penile curvatures of 30-90 degrees. Participants received either 0.58 mg of collagenase clostridium histolyticum or a placebo.
At baseline and at 24- and 52-week follow-up points, the men completed the PDQ and the global assessment of PD (GAPD).
For Study 1, data were available for 303 men at baseline, 284 men at week 24, and 267 at week 52. Analyzed data for Study 2 included 309 men at baseline, 288 at week 24, and 270 at week 52.
The mean age for men in Study 1 was 58.0 ± 8.5 years; for Study 2, it was 57.4 ± 8.4 years. In both studies, over 90% of the men were white. Almost half had been treated for erectile dysfunction (ED).
Men in Study 1 had a mean time since PD diagnosis of 4.3 ± 4.8 years; for Study 2, the mean time was 3.8 ± 3.5 years.
In Study 1, 53.1% of the men felt moderate distress over PD and 30.7% reported severe distress. In Study 2, these numbers were 45.3% and 32.7% respectively.)
Mean PDQ change scores from baseline to week 52 ranged from -1.5 (Study 2) to
-4.6 (Study 1). The PDQ subscales were responsive to change from baseline to week 52.
In Study 1:
• Effect sizes were moderate to large on the Peyronie’s Psychological and Physical Symptoms subscale and the Peyronie’s Symptom Bother subscale.
• The effect size was “quite large” for the Penile Pain subscale for men who reported penile pain at baseline.
In Study 2:
• Effect sizes were moderate on the Psychological and Physical Symptoms and Symptom Bother subscales.
• Effect size was large on the Penile Pain subscale for men who reported penile pain at baseline.
The Psychological and Physical Symptoms and Symptom Bother subscales significantly discriminated patient improvement ratings of the GAPD and degree of penile curvature at weeks 24 and 52.
The PDQ is highly responsive to treatment-related change in men with PD. The data suggest that the PDQ is “sensitive to change in patient-perceived psychological and physical symptom severity, symptom bother, and penile pain.”
The authors added that the PDQ was also able to “discriminate among levels of change in a patient global assessment, penile and penile curvature – both relevant outcomes for PD.”
For the Penile Pain subscale, the greatest responsiveness applied to men with penile pain at baseline. As only a minority of PD patients experience pain, this result was not surprising, the authors said. Also, pain associated with PD tends to resolve on its own. Researchers should keep this point in mind for the future.
The fact that a range of different analyses were used with consistent results “provides assurance that the observed score changes are valid and meaningful.”
“In all, the findings of this study suggest that the PDQ is highly responsive to change in men with PD and can be a useful and effective end point in the clinical setting and in clinical research when evaluating treatments for PD,” the authors concluded.