Crohn's Disease Activity Index Calculator

Crohn's Disease Activity Index Calculator for Gastroenterology. The displayed conventional trial boundary is CDAI <150; the original derivation used <=150 language, so a study protocol must specify its convention. The change calculation is current minus comparison total. Clinical response and objective inflammation need separate assessment.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

This companion interprets an already computed CDAI total and calculates change from a comparison value. It deliberately does not recreate the seven-day diary or make unverified hematocrit/standard-weight adjustments.

When to use this calculator

Use only after the named source assessment is complete and documented. This companion interprets entered totals or subtotals; it does not recreate missing source items or authorize a treatment decision.

Inputs used

  • Documented CDAI total from a completed assessment
  • Comparison CDAI total from the same assessment method

Clinical interpretation

The displayed conventional trial boundary is CDAI <150; the original derivation used <=150 language, so a study protocol must specify its convention. The change calculation is current minus comparison total. Clinical response and objective inflammation need separate assessment.

Worked example

Fictional teaching case. Documented CDAI total from a completed assessment: 346; Comparison CDAI total from the same assessment method: 450. Result: 346 CDAI. At or above conventional active-disease threshold. Change from comparison = -104.00 points. Symptoms and the index do not establish mucosal inflammation or treatment failure.

Limitations and safety notes

CDAI can disagree with objective inflammation. Conventional trial remission uses <150; the original derivation abstract described <=150 as quiescent, so boundary definitions must match the named protocol. Negative totals are accepted rather than silently clamped. This is not a raw-item CDAI calculator.

Frequently asked questions

Does a low CDAI prove intestinal healing?

No. Symptoms and laboratory contributions can disagree with endoscopy, imaging, and other objective inflammatory assessments.

Does this reproduce the full source instrument?

CDAI can disagree with objective inflammation. Conventional trial remission uses <150; the original derivation abstract described <=150 as quiescent, so boundary definitions must match the named protocol. Negative totals are accepted rather than silently clamped. This is not a raw-item CDAI calculator.

References

  • Original CDAI study: eight-variable model and original threshold wording. https://pubmed.ncbi.nlm.nih.gov/1248701/
  • UNITI/IM-UNITI trial conventional CDAI remission threshold below 150. https://www.nejm.org/doi/full/10.1056/NEJMoa1602773

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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