Measurement properties of the childhood bladder and bowel dysfunction questionnaire

Objectives: The childhood bladder and bowel dysfunction questionnaire (CBBDQ) was previously found feasible, structurally valid, with good internal consistency. The purpose of this study was to evaluate the remaining measurement properties according to the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). Methods: A prospective cohort study among parents of children aged 5-12 years was conducted. Calculated were the area under the curve (AUC) (criterion validity, responsiveness, interpretability) and intra-class correlation coefficients (ICCagreement) (construct validity and test-retest reliability). Results: One hundred and seventy-two parents were included from March 2019 to April 2021. Correlating the bladder subscales of the CBBDQ with the Vancouver symptom score for dysfunctional elimination (VSSDES) and proxy-reported pediatric incontinence quality of life (p-PinQ) showed convergent validity (ICCsagreement: 0.76 and 0.74). Divergent validity was found when correlating the bowel subscales of the CBBDQ with the VSSDES (ICCagreement: 0.52). Excellent criterion validity (AUC: 0.98); excellent test-retest reliability (ICCagreement: 0.94) and, at 6 months, fair responsiveness (AUC: 0.74) were found. The minimal important change was 4.5, with cut-off value of 11. Conclusion: The CBBDQ has been developed according to COSMIN standards. The items were defined using the consensus-based ICCS standards and Rome-III criteria. The measurement properties were identified using enough participants. Although interpretability is not considered a measurement property, interpretability aspects are reported here as they refer to what instrument scores mean. The 18-item-CBBDQ met the measurement properties of validity, reliability, and responsiveness, as defined by COSMIN. The CBBDQ is suitable for self-administration by parents, and completion takes little time.