Crohn's Disease Activity Index

The Crohn's Disease Activity Index (CDAI) is a comprehensive, weighted index for assessing disease activity in Crohn's disease. Developed in 1976 by Best and colleagues for the National Cooperative Crohn's Disease Study, the CDAI integrates eight clinical and laboratory variables into a single score ranging from <150 (remission) to >450 (severe activity). Although more complex than symptom-based tools, the CDAI captures the multidimensional nature of Crohn's disease and remains the reference standard for severe disease assessment.