Development, Rasch Analysis and Validation of the Kidney Symptom Burden Questionnaire (KSB-Q)

Background
Increasingly, patient-reported outcome measures (PROMs) are used to monitor chronic kidney disease (CKD) symptoms in routine clinical practice. However, such symptom measurement currently requires completion of multiple, often lengthy, PROMs, which may lead to questionnaire fatigue, lower levels of completion and missing data. Moreover, many CKD-specific PROMs lack evidence of important measurement properties and few were developed using contemporary psychometric methods. The study objective was to develop and validate a short-form kidney symptom burden questionnaire (KSB-Q).

Methods
A cross-sectional item pool survey was distributed to adults (≥18years) with CKD stages 3-5 (including individuals not receiving kidney replacement therapy (KRT), those receiving dialysis and those with a functioning kidney transplant) in England (Birmingham, London, Sheffield and Nottingham), March to September 2022. Rasch measurement was used to assess the psychometric properties of the item pool. Cognitive debriefing interviews were conducted to evaluate content validity.

Results
In total, 419/1,464 participants responded (29% response rate), with 28% receiving dialysis and 30% in receipt of a kidney transplant. Rasch analysis indicated that 9 items, 1 for each of 9 symptom domains (fatigue, pain, memory/concentration, poor sleep, skin problems, gastrointestinal problems, dizziness, restless legs and shortness of breath), formed a PROM with strong psychometric properties (including statistically acceptable reliability, test-retest reliability and validity). Cognitive debriefing and survey responses confirmed content validity encompassing relevance, comprehensiveness and clarity.

Conclusions
The KSB-Q is a 9-item PROM measuring somatic symptoms. The KSB-Q demonstrates strong psychometric properties in patients with CKD stages 3-5, including those not receiving KRT, individuals receiving dialysis and those with a functioning kidney transplant.