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AGA IPMN Risk Stratification (2015)AIMS65 Score APACHE II (AP-specific application)ASGE Choledocholithiasis Risk Stratification ATLAS Score (CDI Treatment Response)Adenoma Detection Rate (ADR) Benchmark Amsterdam II Criteria (Lynch)Anorectal Manometry Interpretation (ARM)Aronchick Bowel Preparation Scale BISAP Score Barrett's Dysplasia Grading (Vienna Classification)Boston Bowel Preparation Scale (BBPS)Bristol Stool Form Scale CD Perianal Disease Activity Index (PDAI)CDI Severity Classification (IDSA/SHEA 2021)CT Severity Index (CTSI — Balthazar)Caecal Intubation Rate (CIR) Benchmark Cambridge Classification (CP — ERCP/EUS/CT)Celiac Disease Serology Interpreter Chicago Classification v4.0 (HRM)Colorectal Cancer TNM Staging (AJCC 8th Edition)Colorectal Submucosal Invasion (Haggitt / Kikuchi)Correa Cascade Staging Cotton Criteria (ERCP Complications)Crohn's Disease Activity Index (CDAI)Crohn's Disease Endoscopic Index of Severity (CDEIS)DeMeester Score (Reflux Monitoring)Distal Contractile Integral (DCI) Calculator Dukes / Modified Astler-Coller Staging (CRC)ERCP Post-Procedure Pancreatitis Risk Score ESD/EMR Curative Resection Criteria (Gastric)Eckardt Score (Achalasia)FODMAP Reintroduction Protocol Indicator Faecal Calprotectin Interpretation Faecal Incontinence Severity Index (FISI)Forrest Classification (Peptic Re-bleed Risk)Fukuoka Consensus Criteria (Pancreatic IPMN)Gastric Cancer TNM Staging (AJCC 8th)Gastric Emptying Scintigraphy Interpretation Glasgow-Blatchford Score (GBS)H. pylori Eradication Confirmation Algorithm Harmless Acute Pancreatitis Score (HAPS)Harvey-Bradshaw (HBI) to CDAI Conversion Harvey-Bradshaw Index (HBI)IBD Steroid Response Predictor (Oxford)IBS Rome IV Diagnostic Criteria IBS Symptom Severity Score (IBS-SSS)Integrated Relaxation Pressure (IRP) Interpreter JNET Classification (NBI Colonoscopy)Kudo Pit Pattern Classification Lichtiger Index (Modified Truelove & Witts)Los Angeles (LA) Classification (GORD)Lynch Syndrome Risk — Revised Bethesda Guidelines Lyon Consensus pH-Impedance Criteria (GORD)Lémann Index (Crohn's Digestive Damage)M-ANNHEIM Classification (Chronic Pancreatitis)MUST (Malnutrition Universal Screening Tool)Magnetic Resonance Index of Activity (MaRIA)Marsh Classification (Celiac Histopathology)Mayo Endoscopic Subscore (MES)Mayo Score (Ulcerative Colitis)Mirizzi Syndrome Classification (Csendes)Modified CT Severity Index (MCTSI)Montreal Classification (Crohn's Disease)Montreal Classification (Ulcerative Colitis)NICE Classification (NBI Polyp Lexicon)NOBLADS Score (Lower GI Bleeding)NRS-2002 (Nutritional Risk Screening)NSAID GI Risk Stratification (ACG/AGA)Nancy Histopathology Index (UC)Nutritional Risk Index (NRI)OLGA / OLGIM Staging (Gastric Gastritis)Oakland Score (Lower GI Bleeding)Oesophageal Cancer TNM Staging (AJCC 8th)Oxford Acute Severe Colitis Criteria (Travis)PREDICT Barrett's Risk Score Paris Classification (GI Lesion Morphology)Partial Mayo Score (UC)Prague C&M Classification (Barrett's)Ranson Criteria Robarts Histopathology Index (RHI)Rockall Score (Acute UGIB)Rutgeerts Score (Post-op Crohn's)SCCAI (Simple Clinical Colitis Activity Index)SIBO Breath Test Interpreter (Glucose/Lactulose)Serrated Lesion Classification (WHO 2019)Short Bowel Syndrome Classification (ESPEN)Siewert Classification (OGJ Tumours)Simple Endoscopic Score for Crohn's Disease (SES-CD)Strate Score (Diverticular Bleed)TPMT / NUDT15 Phenotype-to-Dose Adjustment Thiopurine Metabolite Interpreter Tokyo Guidelines 2018 (Cholangitis Severity)Tokyo Guidelines 2018 (Cholecystitis Severity)Truelove & Witts Criteria UCEIS (UC Endoscopic Index of Severity)Vienna Classification (Crohn's)Wexner (Cleveland Clinic) Constipation Score Wexner Faecal Incontinence Score (CCFIS)Zar Score (CDI Severity Predictor)

Crohn's Disease Activity Index

Crohn's Disease Activity Index (CDAI)

8-variable 7-day diary-based score. Remission = CDAI < 150. For bedside use, consider Harvey-Bradshaw Index (HBI) as the validated same-day surrogate (r = 0.93).

7-Day Diary Values

Total Liquid/Soft Stools (7-day)

Sum of all loose/soft stools across 7 days

Total Abdominal Pain Score (7-day)

Daily score 0–3 summed over 7 days (max 21)

Total Wellbeing Score (7-day)

Daily score 0–4 summed over 7 days (max 28)

Number of Complications

Arthritis, iritis, EN, pyoderma, aphthous ulcers, anal lesion, fistula, fever >37.8°C

Antidiarrhoeals Used?

Abdominal Mass

Patient Sex (for Haematocrit Reference)

HCT (%)

Current Wt (kg)

Standard Wt (kg)

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Primary outcome measure in clinical trials for Crohn's disease therapies

To quantify disease activity and assess response/remission in complex IBD cases

To track therapeutic efficacy over a 7-day retrospective window

Patient Population

Adults with established Crohn's disease. Not validated for pediatric use (PCDAI is used instead) or for patients with isolated perianal disease without luminal activity.

When to Use HBI Instead

Routine clinic visits — CDAI requires a 7-day patient diary, making it difficult for real-time triage; the Harvey-Bradshaw Index (HBI) is better for daily practice

Fibrotic strictures — CDAI captures inflammatory activity; obstructive symptoms from fibrosis may skew the score inappropriately

Primary ileal resection — some categories (like stool count) may be elevated due to bile acid malabsorption rather than active Crohn's

Section 2

Formula & Logic

The 8 Weighted Variables

Number of Liquid/Soft Stools: 7-day sum, weighted x 2.

Abdominal Pain: 7-day sum of severity (0–3), weighted x 5.

General Well-being: 7-day sum (0–4), weighted x 7.

Extra-intestinal Manifestations: Weighted x 20. Includes arthritis, uveitis, erythema nodosum, fever, etc.

Anti-diarrheal Use: Use of Lomotil or Opiates (Yes/No), weighted x 30.

Abdominal Mass: None (0), Questionable (2), Definite (5), weighted x 10.

Hematocrit: Deviation from normal (47 male, 42 female), weighted x 6.

Body Weight: Percentage deviation from standard, weighted x 1.

Scoring Thresholds

< 150	Clinical Remission
-69	Mildly Active Disease
-230	Moderately Active Disease
> 450	Severely Active Disease

Section 3

Pearls/Pitfalls

The "Gold Standard" Burden

The CDAI is the most rigorous and historically significant score in IBD research. However, it is inherently subjective (diary entries for pain and well-being) and can be influenced by IBS-overlap symptoms, leading to high placebo response rates in clinical trials.

Clinical Response Definition

A decrease in CDAI of ≥ 70 to 100 points from baseline is the standard definition of a "clinical response." A total score < 150 points is the definition of "clinical remission."

The Placebo Effect

In many Phase III trials (e.g., SONIC, ACCENT), the placebo response rate based on CDAI was as high as 20–30%. This has led modern researchers to move towards Objective endpoints (e.g., C-Reactive Protein or Endoscopy) alongside the CDAI.

Section 4

Next Steps

CDAI ≥ 220: Perform objective assessment (CRP/Fecal Calprotectin) to confirm inflammation before changing therapy.

CDAI < 150 (Remission): Standard maintenance. Ensure endoscopic healing (CDEIS/SES-CD) is also achieved.

Complementary Tools

Harvey-Bradshaw Index (HBI)

SES-CD (Endoscopic Score)

C-Reactive Protein (CRP) Interpretation

Section 5

Evidence Appraisal

The Original Development

Development of a Crohn's disease activity index. National Cooperative Crohn's Disease Study.

Best WR et al. • Gastroenterology. 1976;70(3):439-44. The foundational study from the NCCDS.

View Source

Statistical Analysis

Rederived values of the eight coefficients of the Crohn's Disease Activity Index (CDAI).

Best WR et al. • Gastroenterology. 1979;77:843-6. Final calibration of the score weights.

View Source

Section 6

Literature

National Cooperative Crohn's Disease Study (NCCDS)

The CDAI was developed in the mid-1970s for the first large-scale multicenter study of Crohn’s disease treatments in the United States. It was the first successful attempt to apply multiple regression analysis to complex subjective and objective clinical data in gastroenterology.

Last Comprehensive Review: 2026

Related Gastroenterology Tools

Glasgow-Blatchford Score

AIMS65 Score

Forrest Classification

Rockall Score

Ranson Criteria

BISAP Score

Harvey-Bradshaw Index

Mayo Score

Truelove & Witts Criteria

Adenoma Detection Rate

Have feedback about this calculator?Let us know.

Crohn's Disease Activity Index

Crohn's Disease Activity Index (CDAI)

8-variable 7-day diary-based score. Remission = CDAI < 150. For bedside use, consider Harvey-Bradshaw Index (HBI) as the validated same-day surrogate (r = 0.93).

7-Day Diary Values

Total Liquid/Soft Stools (7-day)

Sum of all loose/soft stools across 7 days

Total Abdominal Pain Score (7-day)

Daily score 0–3 summed over 7 days (max 21)

Total Wellbeing Score (7-day)

Daily score 0–4 summed over 7 days (max 28)

Number of Complications

Arthritis, iritis, EN, pyoderma, aphthous ulcers, anal lesion, fistula, fever >37.8°C

Antidiarrhoeals Used?

Abdominal Mass

Patient Sex (for Haematocrit Reference)

HCT (%)

Current Wt (kg)

Standard Wt (kg)

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Primary outcome measure in clinical trials for Crohn's disease therapies

To quantify disease activity and assess response/remission in complex IBD cases

To track therapeutic efficacy over a 7-day retrospective window

Patient Population

Adults with established Crohn's disease. Not validated for pediatric use (PCDAI is used instead) or for patients with isolated perianal disease without luminal activity.

When to Use HBI Instead

Routine clinic visits — CDAI requires a 7-day patient diary, making it difficult for real-time triage; the Harvey-Bradshaw Index (HBI) is better for daily practice

Fibrotic strictures — CDAI captures inflammatory activity; obstructive symptoms from fibrosis may skew the score inappropriately

Primary ileal resection — some categories (like stool count) may be elevated due to bile acid malabsorption rather than active Crohn's

Section 2

Formula & Logic

The 8 Weighted Variables

Number of Liquid/Soft Stools: 7-day sum, weighted x 2.

Abdominal Pain: 7-day sum of severity (0–3), weighted x 5.

General Well-being: 7-day sum (0–4), weighted x 7.

Extra-intestinal Manifestations: Weighted x 20. Includes arthritis, uveitis, erythema nodosum, fever, etc.

Anti-diarrheal Use: Use of Lomotil or Opiates (Yes/No), weighted x 30.

Abdominal Mass: None (0), Questionable (2), Definite (5), weighted x 10.

Hematocrit: Deviation from normal (47 male, 42 female), weighted x 6.

Body Weight: Percentage deviation from standard, weighted x 1.

Scoring Thresholds

< 150	Clinical Remission
-69	Mildly Active Disease
-230	Moderately Active Disease
> 450	Severely Active Disease

Section 3

Pearls/Pitfalls

The "Gold Standard" Burden

Clinical Response Definition

A decrease in CDAI of ≥ 70 to 100 points from baseline is the standard definition of a "clinical response." A total score < 150 points is the definition of "clinical remission."

The Placebo Effect

Section 4

Next Steps

CDAI ≥ 220: Perform objective assessment (CRP/Fecal Calprotectin) to confirm inflammation before changing therapy.

CDAI < 150 (Remission): Standard maintenance. Ensure endoscopic healing (CDEIS/SES-CD) is also achieved.

Complementary Tools

Harvey-Bradshaw Index (HBI)

SES-CD (Endoscopic Score)

C-Reactive Protein (CRP) Interpretation

Section 5

Evidence Appraisal

The Original Development

Development of a Crohn's disease activity index. National Cooperative Crohn's Disease Study.

Best WR et al. • Gastroenterology. 1976;70(3):439-44. The foundational study from the NCCDS.

View Source

Statistical Analysis

Rederived values of the eight coefficients of the Crohn's Disease Activity Index (CDAI).

Best WR et al. • Gastroenterology. 1979;77:843-6. Final calibration of the score weights.

View Source

Section 6

Literature

National Cooperative Crohn's Disease Study (NCCDS)

Last Comprehensive Review: 2026

Related Gastroenterology Tools

Glasgow-Blatchford Score

AIMS65 Score

Forrest Classification

Rockall Score

Ranson Criteria

BISAP Score

Harvey-Bradshaw Index

Mayo Score

Truelove & Witts Criteria

Adenoma Detection Rate

Have feedback about this calculator?Let us know.