Predicting the Crohn's disease activity index from the Harvey-Bradshaw Index

Area of Science:

• Gastroenterology
• Clinical Trials
• Biostatistics

Background:

• The Crohn's Disease Activity Index (CDAI) is a standard measure for Crohn's disease severity in clinical trials.
• The Harvey-Bradshaw Index (HBI) offers a simpler alternative for assessing disease activity.
• Previous studies suggested high correlation between CDAI and HBI, but this requires further validation.

Purpose of the Study:

• To develop a predictive model for the Crohn's Disease Activity Index (CDAI) based on Harvey-Bradshaw Index (HBI) values.
• To establish prediction limits for CDAI values derived from HBI.
• To provide a method for more accurate assessment of Crohn's disease activity.

Main Methods:

• Combined data from 224 Crohn's disease patients.
• Performed regression analysis of CDAI on HBI, weighting by the inverse of the estimated CDAI standard deviation.
• Calculated mean and 95% prediction limits of CDAI for each HBI value.

Main Results:

• A linear relationship was found, predicting a 27-unit increase in CDAI for each HBI unit.
• Calculated 95% prediction limits showed diverging lines, encompassing 95% of observations.
• A table was generated detailing CDAI central tendency and prediction limits for all HBI values.

Conclusions:

• A strong but imperfect relationship exists between CDAI and HBI.
• CDAI remains the preferred index for clinical trials.
• HBI is a more user-friendly index for routine clinical practice.