Inflammatory bowel diseases (IBD), which include Crohn's disease (CD) and ulcerative colitis (UC), are increasing in incidence and prevalence worldwide. They often have an onset in young adulthood and are characterised by a prolonged relapsing-remitting course with permanent and progressive intestinal damage. Treatment options for Crohn's disease have expanded over the last decade.
In order to permanently change the natural course of the disease, an important concept that has emerged is the need for an early implementation of effective treatment, followed by a confirmation of therapeutic goal achievement, in order to improve long-term outcomes and prevent disease-related disability. At the cross-sectional level, symptoms correlate poorly with disease activity, making the assessment of disease activity based on symptoms rather suboptimal.
Therefore, objective assessment of inflammation has traditionally relied on endoscopic evaluation of disease activity and observation of mucosal healing. However, reliance on endoscopy alone for repeated assessment of disease activity is limited due to costs, resource intensity, invasiveness of the procedure, and reduced patient acceptability.
Some past studies have compared a symptom-based treatment strategy with a biomarker-based strategy. The use of frequent biomarker measurements to guide therapy escalation has been associated with improved patient outcomes over time.
According to the guideline authors, today biomarkers should no longer be considered experimental and should be an integral part of IBD treatment. Biomarkers are therefore a useful tool to understand and monitor the inflammation status and guide decision-making in patients with Crohn's disease.
Recommendation 1: In patients with CD in symptomatic remission, the AGA suggests a monitoring strategy combining biomarkers and symptoms, rather than relying on symptoms alone (Conditional recommendation, low certainty in evidence).
Recommendation 2: In patients with CD in symptomatic remission with recent endoscopic confirmation of remission (with no change in clinical status, on stable therapy), the AGA suggests using faecal calprotectin <150 μg/g and/or PCR <5 mg/L to exclude active inflammation and to avoid routine endoscopic assessment of disease activity (Conditional recommendation, low to moderate certainty in evidence).
Recommendation 3: In patients with CD in symptomatic remission without recent endoscopic confirmation of remission, the AGA suggests endoscopic evaluation to rule out active inflammation, rather than relying solely on faecal calprotectin or PCR (Conditional recommendation, low to moderate certainty of evidence).
Recommendation 4: In CD patients in symptomatic remission, with elevated biomarkers of inflammation (faecal calprotectin >150 μg/g, PCR >5 mg/L), the AGA suggests endoscopic assessment of disease activity rather than empirical treatment adjustment (Conditional recommendation, low certainty of evidence).
For patients in remission it is recommended to check PCR and FCP every six to twelve months. These tests work best if PCR and FCP levels are compared beforehand with the disease activity detected by endoscopic evaluation.
Recommendation 5: In patients with symptomatically active CD, the AGA suggests a biomarker-based assessment and treatment adjustment strategy, rather than relying on symptoms alone (Conditional recommendation, moderate certainty in the evidence).
Recommendation 6: In CD patients with mild symptoms and elevated biomarkers of inflammation (faecal calprotectin >150 μg/g, CRP >5 mg/L), the AGA suggests an endoscopic assessment of disease activity rather than empirical treatment adjustment (Conditional recommendation, very low certainty in evidence).
Recommendation 7: In CD patients with mild symptoms and normal inflammation biomarkers (faecal calprotectin <150 μg/g, CRP <5 mg/L), the AGA suggests endoscopic assessment of disease activity rather than empirical treatment adjustment (Conditional recommendation, certainty of evidence very low).
Recommendation 8: In CD patients with moderate to severe symptoms, the AGA suggests using faecal calprotectin >150 μg/g or CRP >5 mg/L to rule out active inflammation and adjust treatment, rather than routine endoscopic assessment of disease activity (Conditional recommendation, certainty of evidence low to moderate).
Recommendation 9: In CD patients with moderate to severe symptoms and normal inflammation biomarkers (faecal calprotectin <150 μg/g, CRP <5 mg/L), the AGA suggests endoscopic assessment of disease activity rather than empirical treatment adjustment (Conditional recommendation, low certainty of evidence).
Check PCR and FCP every two to four months for patients presenting with increased symptoms (diarrhoea and abdominal pain) to guide treatment adjustments. Before making major changes to the treatment plan, consider repeating endoscopic or radiological evaluations.
Recommendation 10: In asymptomatic patients with CD after a surgically induced remission in the last 12 months, who are at low risk for post-operative recurrence, or who have 1 or more risk factors for recurrence but are on post-operative pharmacological prophylaxis, the AGA suggests using faecal calprotectin <50 μg/g to avoid routine endoscopic assessment of disease activity (Conditional recommendation, moderate certainty of evidence).
Recommendation 11: In asymptomatic patients with CD after surgically induced remission in the last 12 months, who are at high baseline risk of recurrence and are not on post-operative pharmacological prophylaxis, the AGA suggests endoscopic assessment rather than relying solely on biomarkers (Conditional recommendation, low to moderate certainty of evidence).
For patients after surgery: FCP may therefore be useful to monitor patients at low risk of disease recurrence. However, radiological or endoscopic evaluation should be performed when post-operative recurrence is suspected rather than relying on biomarkers.
Recommendation 12: In patients with CD, the AGA neither advocates nor opposes the use of EHI (Monitr) for inflammation monitoring and treatment decisions (No recommendation, current knowledge gap).
Recommendation 13: In patients with CD, the AGA makes no recommendation for or against a biomarker-based monitoring strategy versus an endoscopy-based monitoring strategy to improve long-term outcomes (No recommendation, knowledge gap).