Development and Psychometric Properties of the Inflammatory Bowel Disease Distress Scale (IBD-DS): A New Tool to Measure Disease-Specific Distress

Abstract

Background Inflammatory bowel disease (IBD) imposes a heavy psychosocial burden, with many patients reporting anxiety, depression, and distress. In diseases such as diabetes, disease-specific distress is associated with concordance with treatments and disease control. IBD distress, distinct from anxiety and depression, is evident in people with IBD. We aimed to develop a questionnaire for assessing IBD-specific distress, validate this against a gold standard distress measure for diabetes, and demonstrate the difference between anxiety, depression, and distress. Methods The 94-item IBD Distress Scale (IBD-DS) was developed through secondary analysis of 3 qualitative data sets from previous IBD studies. Items were then refined through cognitive interviews in 2 stages (n = 15, n = 3). Three supplementary unscored questions were added to enable patients to identify their overall level of distress, their perceived level of disease activity, and their 3 most distressing issues. Subsequently, the 55-item IBD Distress Scale was subjected to test-retest. Two hundred seventy-five people received the test draft IBD-DS, and 168 responded (60.4%). Of these, 136 (82%) returned the retest draft of IBD-DS 3 weeks later. After analysis, further item reduction was informed by response rates, kappa values, and correlation coefficients, and test-retest was repeated. One hundred fifty-four people received the test final 28-item IBD-DS, and 123 people responded (58.8%). Of these, 95 (77%) returned the retest final IBD-DS. Results The 94 items were reduced to 28 items. Good intraclass correlation (ICC) was found between test-retest scores on 72 complete data sets with unchanged disease status (ICC, 0.92; 95% confidence interval, 0.88-0.95). Cronbach's alpha was 0.95, indicating excellent internal consistency. Factor analysis indicated scoring the items as a single domain (score range, 0-168). Conclusion The final IBD-DS performs well and offers a tool for assessing IBD-specific distress.