In order to assess content validity and test-retest reliability of the PPIUS, this study recruited OAB patients to complete a three-day micturition diary including the PPIUS for three consecutive weeks followed by cognitive interviews with participants at selected sites.
During the cognitive interview, participants were debriefed on the entire diary including the instructions, the urgency rating scale of the PPIUS, and their overall experience with the diary and completing it for three weeks. The interviews ascertained that participants interpreted the PPIUS as intended, with most participants reporting that they understood the urgency rating definitions, did not have difficulty rating their urgency grade for each micturition, and found the definitions to be consistent with their interpretation of the rating terms. Participants also reported that they liked and referred to the full urgency rating definitions that were included in the diary instruction packet.
Test-retest reliability of the PPIUS was assessed in 39 patients with OAB receiving pharmacological treatment for their symptoms. Reproducibility was excellent, as evidenced by high ICCs and Spearman’s correlations. In addition, paired t-tests found no difference of PPIUS three-day mean scores between any two weeks supporting that the PPIUS did not demonstrate an acclimation effect.
Although the PPIUS was based on the definition recommend by ICS Standardization of Terminology of Lower Urinary Tract Function Report  and the Committee for Proprietary Medical Products Standardization Sub-Committee , and has been used in other clinical studies [4–6], this is the first attempt in investigating the content validity of the PPIUS from the perspective of OAB patients. While cognitive interview participants were recruited from only two sites, the participants consisted of a good representation of age range, education level, comorbid conditions, and races. In addition, participants also were interviewed shortly after completing the diary for three consecutive weeks, to ensure participants could accurately recall their experience with the diary. The study results are representative and reliable.
Several limitations should be kept in mind when interpreting these results. First, previous studies have indicated that OAB was almost equally prevalent among men and women [17–20]. However, a relatively small percentage (18%) of men participated in the study, while target enrollment for men in OAB clinical trials is typically about 30%. The results could be more confidently generalized to the male patient population if more male patients were interviewed. Another limitation was that the urgency and incontinence continuum was not fully explored, which remained a challenge in assessing urinary urgency. One participant described experiencing incontinence at all level of urgency. Further studies are needed as Starkman et al . pointed out “While some argue that urgency is episodic and maximal, we believe it can be subjectively graded. For example, some episodes of urgency can be suppressed, some persistently require immediate action, and some are so overwhelming that urge incontinence results. Although evidence for such a continuum is lacking, it remains conceptually intuitive.” PPIUS has been included in two completed, one withdrawn, and one ongoing clinical trial as shown in the ClinicalTrial.gov website.