Factors Predicting the Outcome of Disease Activity Assessment in Crohn's Disease

Background: The Crohn's Disease Activity Index (CDAI) has become the gold standard for assessment of disease activity in CD. This study investigated the relationship between CDAI and the physicians' global assessment of disease activity (PGA) and whether different demographic and disease-related factors predict the outcome. Methods: Multiple linear regression analysis was used to investigate the relationship between CDAI and PGA obtained from 405 CD patients. Predictors of the CDAI and the PGA outcome were identified. Results: The correlation between CDAI and PGA was moderate. In patients with CDAI > 150, 72% of the total score were derived froth the subjective variables. The regression coefficients were not significant for 3 of the CDAI variables. In regression analysis, C-reactive protein (CRP), stenosis, smoking, bowel resection, concomitant disease, and gender predicted the CDAI outcome. The PGA outcome was predicted only by CRP, stenosis, and fistula. Conclusions: The correlation between CDAI and PGA was moderate and the subjective variables had a high impact on CDAI. Factors with no obvious relation to inflammatory activity predicted the outcome of CDAI, but not PGA. In trials of CD therapies, separation of subjective (symptoms, well-being) from objective (endoscopy, inflammatory markers) variables should be considered in the assessment of disease activity.