The bladder pain/interstitial cystitis symptom score: development, validation, and identification of a cut score

There is a need to develop a self-report measure that reliably identifies moderate to severe bladder pain syndrome (BPS) patients for inclusion into clinical trials to assess the efficacy of new BPS treatments.

To develop and validate a patient-reported symptom-based instrument, the Bladder Pain/Interstitial Cystitis Symptom Score (BPIC-SS), for clinical trial eligibility of BPS patients.

Stage 1: Qualitative concept elicitation (CE) interviews were conducted with BPS patients in France (n=12), Germany (n=12), and the United States (US) (n=20), and overactive bladder (OAB) (n=10) patients in the US for comparison. Stage 2: Cognitive debriefing (CD) interviews were performed with US BPS patients (n=20). Stage 3: An observational study with 99 BPS, 99 OAB, and 100 healthy participants in the US was used to perform item reduction, identify cut scores, and validate the measure. A cut score was defined using logistic regression and receiver operating characteristic curves. Psychometric properties, including test-retest reliability, were assessed.

In addition to the BPIC-SS, the Pelvic Pain and Urgency/Frequency Patient Symptom Scale, the Interstitial Cystitis Symptom Index, a Clinician Global Impression of Severity, and a Patient Global Impression of Change were included in the observational study.

In CE, reported symptoms were bladder pain, persistent urge to urinate, and high urinary frequency. In CD, 13 items were deleted, and 15 were retained. Based on validation analyses, qualitative findings, and clinical relevance, the instrument was reduced to eight items that had strong sensitivity (0.72) and specificity (0.86) with a cut score ≥19 to determine clinical trial inclusion. Psychometric properties were strong.

The BPIC-SS is a reliable, valid, and appropriate questionnaire to select BPS/interstitial cystitis patients for clinical trials.