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.