A Comprehensive Evaluation of the Impact of Crohnʼs Disease and Its Treatment on Patients Is Achieved Using a Combination of the CDAI and IBDQ

Abstract

Purpose: Diarrhea, abdominal pain, and weight loss are common symptoms of Crohn's disease (CD); the most commonly used measure for these symptoms is the CD Activity Index (CDAI). CD also greatly impacts patients’ physical, emotional, and social functioning.1 These aspects are measured using the Inflammatory Bowel Disease Questionnaire (IBDQ).2 This analysis compared and contrasted CDAI and IBDQ information using data from PRECiSE 2. Methods: In PRECiSE 2, patients with a clinical response at Wk 6 following induction with certolizumab pegol (CZP) were randomized to CZP (N = 215) or placebo (PBO; N = 210) every 4 wks up to Wk 24.3 CDAI and IBDQ data were collected at Wks 0, 6, 16, and 26. Correlations were evaluated at Wk 26, or at baseline, using Pearson's correlation for CDAI total score and IBDQ total or domain scores, and Spearman's rank correlation for CDAI and IBDQ items scores. Missing data were not imputed. Correlation coefficients (R) were termed moderate (≥0.3) or high (≥0.5).4 Results: CDAI and IBDQ total scores correlated moderately at baseline (R =− 0.344; N = 255) and highly at Wk 26 (R =− 0.603). CDAI total score (N = 255) correlated more with the bowel (R =− 0.593) and systemic (R =− 0.566) symptom domains of IBDQ than with the IBDQ emotional (R =− 0.517) and social (R =− 0.469) function domains. Abdominal pain, diarrhea, and general well-being, assessed in both measures, were highly correlated (R =− 0.610 to −0.721; N = 244). Weakly correlated items (R <0.3) included CDAI clinical objective measures (taking medication for diarrhea, abdominal mass, hematocrit, and low body weight) and some IBDQ emotional and social function items (passing gas, rectal bleeding, accidental soiling, weight problems, and lack of understanding from others). Conclusion: The CDAI and IBDQ assess interrelated but nonidentical aspects of CD. The CDAI reflects physical more than emotional or social aspects, while the IBDQ covers all aspects but is less comprehensive than the CDAI for clinical objective measures. Both instruments in combination provide a comprehensive evaluation of the impact of CD and its treatment. This research was funded by UCB.