Defining Moderate Disease Activity and Severity in Crohn's Disease and Ulcerative Colitis.

Area of Science:

• Gastroenterology
• Inflammatory Bowel Disease (IBD) research
• Clinical trial methodology

Background:

• Real-world data indicate biologics are more effective in moderate versus severe inflammatory bowel disease.
• Lack of a standardized definition for moderate disease hinders research and optimal treatment strategies.
• Biologic therapy is a key treatment for moderate to severe Crohn's disease and ulcerative colitis.

Purpose of the Study:

• To systematically review existing literature for definitions of moderate Crohn's disease (CD) and ulcerative colitis (UC).
• To identify consensus on distinguishing moderate from mild or severe disease in clinical practice.
• To inform the development of a clinically relevant definition for moderate CD and UC.

Main Methods:

• Systematic literature review (SLR) of observational and interventional studies (2015 onwards).
• Targeted literature review (TLR) of phase 3 trials (2000 onwards).
• Expert consensus meeting to discuss disease severity assessment.

Main Results:

• Identified 6 definitions for moderate CD and 16 for moderate UC across 140 SLR and 101 TLR publications.
• Most definitions relied on Crohn's Disease Activity Index (CDAI) for CD and Mayo score for UC.
• Definitions lacked inclusion of quality of life, disease course, or prognosis, which experts deemed important.

Conclusions:

• A clear, clinically meaningful definition of moderate disease is needed for both CD and UC.
• Standardized definitions will improve identification of patients who could benefit from biologic therapies.
• Further research should incorporate patient-reported outcomes and disease trajectory into severity assessments.