Evaluation of short-term responsiveness and cutoff values of Inflammatory Bowl Disease Questionnaire in Crohn's disease

Background: The inflammatory bowel disease questionnaire (IBDQ) is a frequently used outcome parameter in clinical trials. Whereas the validity and reproducibility of the IBDQ have been extensively studied, there are limited data oil its short-term responsiveness and cutoff values for remission and partial clinical response. Methods: The IBDQ score and its bowel (BD), systemic (SysD), emotional (ED), and social (SocD) dimensions were tested for responsiveness in a cohort of 224 patients with Crohn's disease (CD) treated with infliximab for refractory luminal disease. Changes in the IBDQ score and its dimensions 4 weeks after therapy were analyzed and correlated with changes in the Crohn's Disease Activity Index (CDAI). The responsiveness ratios of the IBDQ and its dimensions were analyzed. Using regression line with Delta CDAI, the cutoff values for the IBDQ remission and response were calculated. Results: Overall, there was a good correlation between the CDAI and IBDQ at week 0 (correlation coefficient, 0.69; P < .001) and week 4 (-0.76: P < .001) and change after 4 weeks (0.74; P < .001). The correlation coefficients for Delta CDAI and changes in BD, SysD, ED, and SocD were 0.753. 0.552, 0.620, and 0.631, respectively; all P < 0.001. The responsiveness ratios for Delta IBDQ, BD, SysD, ED, and SocD were 2.6, 2.1, 1.9. 1.7, and 1.9, respectively. Regression line for the IBDQ (r = -0.76 P < .001) resulted in a cutoff value for remission of 168 points and for Delta IBDQ resulted in a cutoff value of 22 and 27 points for clinical improvement based on Delta CDAI >=-70 and >=-100 points. Conclusions: The IBDQ is a responsive instrument for reflecting quick change in the quality of life of patients with CD. Cutoff values for the IBDQ remission and partial response were 168 and >= 27 points.