Validity and reliability of the patient's perception of intensity of urgency scale in overactive bladder

• To assess the measurement characteristics of the Patient Perception of Intensity of Urgency Scale (PPIUS) in patients with overactive bladder (OAB).

• Adult women with at least a 3-month history of OAB. The design was a 4-week, double-blind, randomized, placebo-controlled trial of transdermal oxybutynin, with a 2-week placebo run-in and 8-week, open-label extension. • Symptom improvement was assessed using 3-day bladder diaries incorporating the PPIUS, and disease-specific health-related quality of life was assessed using the King's Health Questionnaire (KHQ). Convergent validity was shown by correlation with the KHQ, and other bladder diary variables. Known groups validity was assessed by comparison of baseline mean urge ratings, and urgency episode frequency for continent and incontinent patients, and by comparison with the same measures from a historical control group of 40 asymptomatic female volunteers. • Between- and within-groups responsiveness was assessed using standardized effect sizes (Cohen's d and effect size r). Reliability was assessed for the two arms of the trial at different time points and intervals, using intraclass correlation (ICC) and a t-test for the difference between mean scores.

• In total, 96 women were randomized. Urgency episode frequency showed moderate correlation with total KHQ score (r = 0.500, P < 0.001) and with daytime and night-time voiding frequency. • There were significant differences in continent and incontinent subgroups for mean urge ratings (difference in means, -0.61/void, P < 0.001), and urgency episodes (difference in means, -2.67 episodes/day, P < 0.001), as well as between OAB patients and normal controls (mean urge rating: difference in means 1.22 per void, P < 0.001; urgency episodes: difference in means 2.93 episodes/day, P < 0.001). • Between-groups analysis of effect size found that urgency episode frequency (d = 0.679, r = 0.321) was more responsive than mean urge rating (d = 0.480, r = 0.233). In both subgroups, urgency episode frequency (d = 0.421-0.454, r = 0.206-0.222) had better within-groups responsiveness than mean urge rating. • Urgency episodes (ICC, 0.65-0.81) were measured more reliably than urgency urinary incontinence episodes (ICC, 0.50-0.65).

• Assessment of urgency episodes using the PPIUS shows good reliability, excellent known groups validity, high responsiveness and convergence with subjective measures of severity. • PPIUS is freely available, and should be useful in both clinical practice and research studies when assessing women with urgency, with or without urgency urinary incontinence.