How is ulcerative colitis severity graded using the Truelove‑Witts criteria and the Mayo Clinic score?

Ulcerative Colitis Severity Assessment

Use the Truelove-Witts criteria to classify disease severity (mild, moderate, severe) based on systemic toxicity markers, and use the Mayo Clinic Score (0-12 scale) to quantify overall disease activity combining clinical symptoms with endoscopic findings. These two systems serve complementary purposes in UC management. 1

Truelove-Witts Severity Index

The Truelove-Witts criteria, established in 1955, provide objective criteria for assessing acute severe colitis, determining need for hospitalization, and guiding corticosteroid therapy. 1 This system classifies disease into three categories based on systemic toxicity:

Mild Disease

• Bloody stools: <4 per day 1
• Pulse: <90 bpm 1
• Temperature: <37.5°C 1
• Hemoglobin: >11.5 g/dL 1
• ESR: <20 mm/hr 1
• CRP: Normal 1

Moderate Disease (Between Mild and Severe)

• Bloody stools: 4-6 per day 1
• Pulse: ≤90 bpm 1
• Temperature: ≤37.8°C 1
• Hemoglobin: ≥10.5 g/dL 1
• ESR: ≤30 mm/hr 1
• CRP: ≤30 mg/L 1

Severe Disease

• Bloody stools: ≥6 per day 1
• Pulse: >90 bpm 1
• Temperature: >37.8°C 1
• Hemoglobin: <10.5 g/dL 1
• ESR: >30 mm/hr 1
• CRP: >30 mg/L 1

Key clinical application: The Truelove-Witts criteria excel at identifying patients requiring hospitalization and intravenous corticosteroids by focusing on systemic toxicity markers rather than just local intestinal symptoms. 1

Mayo Clinic Score (Full Mayo Score)

The Mayo Score is a composite 0-12 point system that includes four components, each scored 0-3, widely used in both clinical trials and practice. 2

Four Components (Each Scored 0-3)

1. Stool Frequency 2
2. Rectal Bleeding 2
3. Physician's Global Assessment 2
4. Endoscopic Findings (Mayo Endoscopic Subscore) 2

Mayo Endoscopic Subscore Definitions

• Grade 0: Normal or inactive disease 2
• Grade 1: Mild disease (erythema, decreased vascular pattern, mild friability) 2
• Grade 2: Moderate disease (marked erythema, absent vascular pattern, friability, erosions) 2
• Grade 3: Severe disease (spontaneous bleeding, ulcerations) 2, 3

Clinical Definitions Using Mayo Score

Clinical Remission: Total Mayo score ≤2 with no individual subscore >1 1, 2

Clinical Response: Reduction of baseline Mayo score by ≥3 points AND a decrease of ≥30% from baseline with either:

• Decrease of at least 1 point on rectal bleeding subscale, OR
• Absolute rectal bleeding score of 0 or 1 1, 2

Mucosal Healing: Endoscopic subscore ≤1 1, 2

Partial Mayo Score

The Partial Mayo Score excludes the endoscopic component, using only the three non-invasive parameters (stool frequency, rectal bleeding, physician's global assessment) for a maximum of 9 points. 2 A Partial Mayo Score <1 indicates remission. 1

Practical Application Algorithm

Step 1: Initial Severity Classification

Use Truelove-Witts criteria at presentation to determine:

• Outpatient management (mild disease) 1
• Oral corticosteroid therapy (moderate disease) 1
• Hospitalization and IV corticosteroids (severe disease) 1

Step 2: Quantitative Disease Monitoring

Use Mayo Score to:

• Establish baseline disease activity (requires endoscopy for full score) 2
• Monitor treatment response at 2-4 weeks (can use Partial Mayo Score) 4
• Define therapeutic endpoints (remission, response) 1, 2

Step 3: Endoscopic Reassessment

Perform colonoscopy at 6-12 months to evaluate mucosal healing using Mayo Endoscopic Subscore. 3 The most inflamed segment determines the overall endoscopic score. 1

Alternative Validated Endoscopic Scores

While the Mayo Endoscopic Subscore is extensively used, the Ulcerative Colitis Endoscopic Index of Severity (UCEIS) is formally validated and may offer superior accuracy. 1

UCEIS evaluates three variables (0-8 point scale): 1

• Vascular pattern (0-2) 1
• Bleeding (0-3) 1
• Erosions and ulcers (0-2) 1

Advantages of UCEIS: Developed following rigorous methodology, shows stronger correlation with clinical outcomes and long-term prognosis compared to Mayo Endoscopic Score, particularly in detecting early mucosal healing when ulcers become smaller and shallower. 5

Common Pitfalls and Caveats

Interobserver variability: Mayo Endoscopic Score agreement can vary markedly between endoscopists, particularly in distinguishing mild from moderate friability. 1, 2 The UCEIS demonstrates better interobserver agreement. 5

Clinical-endoscopic discordance: Patients may achieve clinical remission (symptomatic improvement) while maintaining severe endoscopic disease (Mayo 3), requiring continued therapy escalation rather than assuming adequate treatment. 3

Truelove-Witts limitations: The original classification lacks well-defined endoscopic descriptors and focuses primarily on systemic toxicity rather than mucosal inflammation severity. 1

Timing of assessment: Clinical improvements with corticosteroids can be seen within 2 weeks, but endoscopic reassessment should occur at 6-12 months to properly evaluate mucosal healing. 3, 4

Fecal calprotectin correlation: Calprotectin >150-250 mg/g can identify persistent endoscopic inflammation in asymptomatic patients, though false positives exist. 3 The Mayo score correlates strongly with fecal calprotectin (r = 0.63), with correlation strengthening when including the endoscopic subscore (r = 0.90). 4