Validation of the IBD-Control Questionnaire across different sociodemographic and clinical subgroups: Secondary analysis of a nationwide electronic survey.

Abstract

The IBD-Control Questionnaire is a simple, generic measure of patient-perceived disease control used increasingly in clinical practice and research. We aimed to address knowledge gaps in its psychometric performance, to ensure that it can be used with confidence in a variety of contexts. We analysed 7,341 responses to the IBD Registry COVID-19 survey, sent to 40,911 patients who completed an online self-assessment tool during the pandemic. Questions covered demographics, comorbidities, IBD sub-type, IBD-Control Questionnaire and symptom scores (CD-PRO2 or UC-PRO2). Psychometric properties of IBD-Control-8 were tested overall and within subgroups (CD, UC and IBD-U; male and female; ≤65 and > 65 years; number of co-morbidities; deprivation status). Internal consistency was very strong overall (α: 0.84, ω: 0.89) and for each subgroup (α range: 0.81-0.85; ω: 0.86-0.90). Construct validity was demonstrated by moderate correlation of each item with global rating (VAS) (rs range: 0.47 to 0.65), strong correlation between IBD-Control-8 score and VAS (rs=0.74), moderate-to-strong with PRO2 scores (CD: rs = -0.718; UC: rs = -0.602) and significantly higher IBD-Control-8 scores for PRO2-remission versus -active, consistent across subgroups. Exploratory and Confirmatory Factor Analyses demonstrated a two-factor model (items loading onto 'Health-related Quality of Life' [HRQoL] or 'Treatment' domains). Extensive tests for factorial invariance confirmed consistency. IBD-Control-8 is a psychometrically robust scale which can be used across a range of populations. It offers a quick, reliable and valid method of assessing patient-perceived control. The construct of "control" includes traditional HRQoL and a novel domain relating to treatment perception.