Pain and Urinary Symptoms Should Not be Combined into a Single Score: Psychometric Findings from the MAPP Research Network

Abstract

The purpose of this study was to create symptom indexes, that is scores derived from questionnaires to accurately and efficiently measure symptoms of interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome, collectively referred to as urological chronic pelvic pain syndromes. We created these indexes empirically by investigating the structure of symptoms using exploratory factor analysis. As part of the MAPP (Multi-Disciplinary Approach tothe Study of Chronic Pelvic Pain) Research Network 424 participants completed questionnaires, including GUPI (Genitourinary Pain Index), ICSI (Interstitial Cystitis Symptom Index) and ICPI (Interstitial Cystitis Problem Index). Individual items from questionnaires about bladder and pain symptoms were evaluated by principal component and exploratory factor analyses to identify indexes with fewer questions to comprehensively quantify symptom severity. Additional analyses included correlating symptom indexes with symptoms of depression, which is a known comorbidity of patients with pelvic pain. Exploratory factor analyses suggested that the 2factors pain severity and urinary severity provided the best psychometric description of items in GUPI, ICSI and ICPI. These factors were used to create 2symptom indexes for pain and urinary symptoms. Pain, but not urinary symptoms, was associated with symptoms of depression on multiple regression analysis, suggesting that these symptoms may impact patients with urological chronic pelvic pain syndromes differently (B ± SE for pain severity =0.24±0.04, 95% CI 0.16-0.32, β = 0.32, p <0.001). Our results suggest that pain and urinary symptoms should be assessed separately rather than combined into 1 total score. Total scores that combine the separate factors of pain and urinary symptoms into 1 score may be limited for clinical and research purposes.