Maximizing the diagnostic information from biopsies in chronic inflammatory bowel diseases: recommendations from the Erlangen International Consensus Conference on Inflammatory Bowel Diseases and presentation of the IBD-DCA score as a proposal for a new index for histologic activity assessment in ulcerative colitis and Crohn\u2019s disease

Abstract

Chronic idiopathic inflammatory bowel disease (IBD) cases are on the rise, with approximately 6.8 million people diagnosed in 2017 [1]. Diagnosing the two main forms of IBD, ulcerative colitis (UC) and Crohn’s disease (CD), involves a combination of clinical history, laboratory findings, imaging, endoscopy and histology [2]. The histopathological diagnosis of IBD is based on a combination of microscopic findings, with consideration of clinical data that include the patient’s age, symptoms, duration of symptoms and endoscopic results [3–17]. CD is a chronic, progressively destructive disease with an intermittent course in most cases. UC is most often described as relapsing and remitting, with symptoms of active disease that alternate with periods of clinical quiescence called remission [18, 19]. Until recently, therapeutic strategies in both diseases aimed to achieve adequate control of gastrointestinal inflammation. In recent years, however, mucosal healing has become the key treatment goal in IBD. It is associated with improved clinical outcomes, prolonged remission, fewer hospitalizations and decreased probability for surgery [20–36]. Patients with mucosal healing have lower rates of clinical relapse compared to those with evidence of active or quiescent disease. Endoscopic evaluation without histology, however, may be insufficient to deem treated IBD mucosa as completely healed [34, 36]. Furthermore, histologic identification of active disease has also been shown to better predict the development of neoplasia in patients with UC compared to endoscopic assessment of activity [30–32, 34, 37]. The fact that concordance between endoscopic and histological remission is moderate only—with histological remission being superior—underscores the necessity of incorporating histologic methods of activity scoring into clinical trials [34]. In fact, in 2016, the Food and Drug Administration (FDA) of the United States Department of Health and Human Services recommended that histologic assessment be used in conjunction with endoscopy [38]. A number of histologic indices for assessing activity in UC and CD exist. Nevertheless, they all have limitations, including lack of full validation, difficulty of usage and heterogeneity in their standards for distinguishing between quiescent disease and histologic normalization [39, 40]. Moreover, there is also a need for standardization of biopsy procedures in UC and CD on the endoscopic end. Recommendations for biopsy procedures and IBD scoring exist from many internationally recognized organizations, such as the European Crohn’s and Colitis Organisation (ECCO), the World Gastroenterology Organisation (WGO), the British Society of Gastroenterology (BSG), the International Organization for the Study of Inflammatory Bowel Diseases (IOIBD), the American College of Gastroenterology (ACG) and the American Society for Gastrointestinal Endoscopy (ASGE). Some of them have recently been updated [17, 19, 28, 41–51]. However, in practice, these existing recommendations are not widely adhered to and there is still a need for standardizing the number of IBD biopsies, the locations they are taken from and an accepted validated IBD histologic assessment tool for daily practice. For these reasons, the objectives of the 2020 International Consensus Conference on IBD Activity Scoring were (i) to review existing recommendations and to agree upon ten recommendations with the highest impact to maximize diagnostic information from biopsies for UC and CD and (ii) to agree on a simple, histologic scoring system for both types of IBD that is able to distinguish between quiescent disease and mucosal healing and has potential for use in daily routine practice as well as for clinical trials.