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The guideline was developed by a multidisciplinary panel and consists of 11 conditional recommendations for the use of biomarkers in the management of Crohn disease.
A new evidence-based guideline from the American Gastroenterological Association (AGA) recommends the use of blood and stool-based biomarkers to help manage Crohn disease (CD).
Developed by a multidisciplinary panel of content experts and guideline methodologists using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework, the guideline makes 11 conditional recommendations for the use of biomarkers alongside colonoscopy and imaging studies in patients with CD.1
“Patients’ symptoms do not always match endoscopic findings, so biomarkers are a useful tool to understand and monitor the status of inflammation and guide decision making in patients with Crohn's disease,” said Siddharth Singh, MD, MS, assistant professor of clinical medicine at the University of California San Diego School of Medicine.2
The US Centers for Disease Control and Prevention estimates 3.1 million adults in the United States have been diagnosed with inflammatory bowel disease (IBD), including CD and ulcerative colitis. There is no single definitive test to confirm the presence of IBD, so diagnosis and disease management are often based on a combination of tests, including endoscopy, biopsy, and imaging. Serum and fecal biomarkers have been considered speculative surrogates of endoscopic activity assessment, although a lack of comprehensive examination of their optimal use in clinical practice has limited their utility thus far.1,3,4
The guideline is intended to inform the role of commonly used serum and fecal biomarkers as surrogates for endoscopic disease activity in patients with an established diagnosis of CD. It was devised by a guideline panel and an evidence synthesis panel of clinical and methodological experts using GRADE framework for diagnostic tests and strategies.1
Specifically, the panel focused on biomarkers widely used for assessing disease activity and making treatment decisions, measurable in easily accessible tissue or body fluid compartments, and commercially available in the United States. These included serum C-reactive protein (CRP), fecal calprotectin, and the Endoscopic Healing Index (EHI, Monitr).1
The performance of individual biomarkers was examined in unselected cohorts of patients with CD and for initial assessment of postoperative recurrence of CD after surgically induced remission. The panel examined the cross-sectional performance of each biomarker against the gold standard of endoscopic activity, defined as a Simple Endoscopic Score for Crohn’s Disease ≥3.1
The guideline and evidence synthesis panels used an iterative process to develop focused clinical questions deemed relevant for clinical practice to be addressed in the guideline, relating to the diagnostic accuracy and utility of commonly used serum or stool biomarkers. A comprehensive search of Ovid Medline In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Embase, and Wiley Cochrane Library from inception to November 21, 2021, was completed to find relevant randomized controlled trials or observational studies of diagnostic accuracy.1
Investigators collected data on patient population and phenotype, biomarker, reference standard outcome, and test performance for each eligible study, all of which served as evidence used to formulate the guideline recommendations. Based on the Evidence-to-Decision framework, the panel considered the certainty of evidence, balance of benefit and harms, patient values and preferences, and feasibility, acceptability, equity, and resource use.1
The guideline panel made 11 conditional recommendations, all of which they reached a consensus on. In patients with CD in symptomatic remission, the panel suggests use of a biomarker- and symptom-based monitoring strategy instead of symptoms alone. For patients in symptomatic remission, the guideline suggests fecal calprotectin <150 μg/g and normal CRP rules out active inflammation, avoiding the need for endoscopic evaluation to assess disease activity. However, investigators pointed out elevated biomarkers in this setting merit confirmation with endoscopy before treatment adjustment.1
In patients with CD with mild symptoms, the panel decided neither normal nor elevated biomarkers alone are sufficiently accurate to determine endoscopic activity. In patients with CD with moderate to severe symptoms, elevated fecal calprotectin or serum CRP suggests endoscopic activity, precluding routine endoscopic assessment for disease activity.1
In patients with CD in surgically induced remission in low-risk patients on pharmacologic prophylaxis, the guideline suggests a normal fecal calprotectin can reliably rule out endoscopic recurrence. In other postoperative settings, the panel suggests endoscopic assessment for establishing postoperative recurrence.1
“Based on this guideline, biomarkers are no longer considered experimental and should be an integral part of IBD care,” said Ashwin Ananthakrishnan, MBBS, MPH, MD, of Massachusetts General Hospital.2 “This is a win for Crohn’s disease patients. Biomarkers are usually easier to obtain, less invasive, more cost-effective than frequent colonoscopies and can be assessed more frequently for tighter disease control and better long-term outcomes in Crohn’s disease.”