Validation of a Modified National Institutes of Health Chronic Prostatitis Symptom Index to Assess Genitourinary Pain in Both Men and Women

Objectives: To date, separate condition-specific instruments have been used to assess severity of symptoms, in men and women with urological pain conditions. We developed a single instrument that can be used to assess treatment response in clinical trials and cohort studies that involve both genders. Methods: We developed the Genitourinary Pain Index (GUPI) by modifying and adding questions to the National Institutes of Health-Chronic Prostatitis Symptom Index. To assess discriminant validity, concurrent validity, and reliability, we administered the GUPI to 1653 men and 1403 women in a large managed care population. To assess responsiveness, we administered the GUPI to 47 men and women who completed a National Institutes of Health-sponsored trial of pelvic floor physical therapy. Results: The GUPI discriminated between men with chronic prostatitis or interstitial cystitis, those with other symptomatic conditions (dysuria, frequency, chronic cystitis), and those with none of these diagnoses (P <.05). It also discriminated between women with interstitial cystitis, those with incontinence, and those with none of these diagnoses (P <.05). The GUPI demonstrated good internal consistency within subscale domains, and GUPI scores correlated highly with scores on the Interstitial Cystitis Symptom Index and Problem Index. The GUPI was highly responsive to change, and the change in score was similar in both male and female responders. A reduction of 7 points robustly predicted being a treatment responder (sensitivity 100%, specificity 76%). Conclusions: The GUPI is a valid, reliable, and responsive instrument that can be used to assess the degree of symptoms in both men and women with genitourinary pain complaints.