Test-retest reliability and discriminant validity for the Brazilian version of “The Interstitial Cystitis Symptom Index and Problem Index” and “Pelvic Pain and Urgency/Frequency (PUF) Patient Symptom Scale” instruments

BACKGROUND The purpose is to evaluate the psychometric properties of reliability and discriminant validity of the Brazilian Portuguese versions of two instruments used in the diagnosis of interstitial cystitis (IC): "The Interstitial Cystitis Symptom Index and Problem Index" (The O'Leary-Sant), and "Pelvic Pain and Urgency/Frequency (PUF) Patient Symptom Scale". METHODS Three groups of patients were examined: a study group (subjects with IC), control group 1 (individuals with at least one IC symptom), and control group 2 (subjects without IC symptoms). Test-retest stability was evaluated at intervals of 3 to 7 days in the study group. Discriminant validity was examined in all three groups. RESULTS The intraclass correlation coefficient (ICC) [95% confidence interval (CI)] results were 0.56 (range, 0.21-0.78) for The O'Leary-Sant Symptom Index, 0.48 (range, 0.10-0.73) for The O'Leary-Sant Problem Index, and 0.49 (range, 0.12-0.74) for the PUF. To analyze discriminant validity between groups, we used Fisher's exact test and odd ratio (OR) to identify differences. We obtained a P value<0.0001, which indicated that the null hypothesis was rejected; in other words, there was evidence that at least two different groups were compared to the proportion of patients with IC. CONCLUSIONS The analyzed instruments did not reach appropriate values for reliability. Future studies are needed to analyze the psychometric measures of these instruments on a larger sample of patients with IC.