Responsiveness is the ability of an outcome measure to detect clinically significant changes. The objective of this study is to compare the responsiveness of several validated incontinence, pelvic floor and quality of life outcome measures in women undergoing surgery for stress urinary incontinence (SUI).
MATERIALS AND METHODS:
This is an ancillary analysis of data obtained from a multi-center randomized trial comparing TVT with TOT for the treatment of SUI. 170 patients were randomized and 162 subjects were followed for at least one year after surgery and are the subject of this study. All patients completed the following outcome measures at baseline and again one year after surgery: Incontinence Severity Index (ISI), Pelvic Floor Distress Inventory short form (PFDI-20), Pelvic Floor Impact Questionnaire short form (PFIQ-7), the POP/Urinary Incontinence Sexual Function Questionnaire (PISQ-12), a 3-day bladder diary yielding incontinence episodes per week (IEW), and both the mental and physical components of the Short Form 12 (SF-12). The changes in total scores for each of these instruments as well as the Urogenital Distress Inventory (UDI-6) and Urinary Incontinence Questionnaire (UIQ-7) subscales of the PFDI-20/PFIQ-7 were evaluated. All patients also completed the Patient Global Index of Improvement (PGI-I) at one year. Responsiveness was assessed by comparing the standardized response mean (SRM) for each instrument. We also compared each measure's ability to discriminate between those who improved versus those who did not as assessed by PGI-I using the area under the receiver operating curve (AUC).
Per the PGI-I, 13% of patients were worsened or not improved, 7% were “somewhat better”, 24% were “much better” and 56% were “very much better” one year after surgery. The ISI, PFDI-20, UDI-6, PFIQ-7 and UIQ-7 demonstrated excellent responsiveness (SRM > 1.0), while the PISQ-12 and IEW on the bladder diary showed moderate responsiveness (SRM 0.58 & 0.50, respectively) and the scales of the SF-12 demonstrated poor responsiveness (0.22 & 0.11). (Table) Change in diary IEW demonstrated the greatest ability to discriminate between those who improved and those who did not (AUC .97). Change in IEW also had the greatest correlation with a patient's subjective impression of improvement as measured by the PGI-I (r = .50, P = .001).
The ISI, PFDI-20 and UDI-6 have the greatest responsiveness after surgery for SUI, while the SF-12 is not responsive in this population. The IEW on a 3 day bladder diary demonstrated the greatest ability to discriminate between those patients who considered themselves improved from those who did not.