S0647 Endoscopic and Histologic Activity Predict Inflammatory Bowel Disease-Related Hospitalization: A Nationwide Study

Abstract

INTRODUCTION: Measures of mucosal healing are critical for the study of inflammatory bowel disease (IBD). Since endoscopic and histologic activity do not always concur, it is important to measure their individual associations with IBD outcomes that reflect disease activity. Using nationwide Swedish patient registers, we evaluated the influence of baseline endoscopic and histologic activity on IBD-related hospitalization. METHODS: In a cohort study of patients with incident Crohn's disease (CD), ulcerative colitis (UC), and IBD-unclassified (IBD-U) during 1969–2017, we linked endoscopic inflammation in the Swedish Quality Register for Inflammatory Bowel Disease (SWIBREG) registry with histologic inflammation in the Epidemiology Strengthened by histoPathology Reports in Sweden (ESPRESSO) registry. We established and validated a SNOMED-based histology score to predict endoscopic scores [Mayo endoscopic subscore (MES) in UC and IBD-U; SWIBREG-CD score in CD (SCS)], and dichotomized these data based on Bayesian rule list scores. We assessed the impact of baseline endoscopic activity and histologic activity on IBD-related hospitalization. RESULTS: We identified 48,449 individuals with incident IBD linked to a histology record in ESPRESSO and 5225 individuals linked to an endoscopic assessment in SWIBREG (Table 1). We created and validated models to calculate a SNOMED-based histology score (ROC for predicting a non-zero endoscopic score: UC 0.80, CD 0.70, IBD-U 0.76). In a subset of 2741 individuals with an IBD diagnosis and a corresponding histology and endoscopy score, baseline scores were associated with time to IBD-related hospitalization (endoscopy log-rank UC P < 0.001, CD P = 0.020, IBD-U P < 0.001; histology log-rank UC P = 0.018, CD P = 0.960, IBD-U P = 0.034; Figure 1). In the larger sample of 48,449 individuals with SNOMED-based histology scores, we observed similar associations with time to IBD-related hospitalization, with a strong association in UC and CD, but no association in IBD-U (log-rank UC P < 0.001, CD P < 0.001, IBD-U P = 0.996; Figure 2). CONCLUSION: In this study using nationwide patient registers, we linked clinical, endoscopic, and histologic data for the study of IBD. Baseline endoscopy and histology scores at IBD diagnosis were associated with time to IBD-related hospitalization, particularly in UC. These data are critical for the further evaluation of longitudinal measures of mucosal healing on IBD outcomes.Table 1.: Description of registry linkageFigure 1.: Time to IBD-related hospitalization by baseline endoscopic scores [a, Mayo endoscopic score (MES) and SWIBREG-CD score (SCS)] and histology scores [b; n = 5225] stratified by IBD subtype.Figure 2.: Association between histology score and time to IBD-related hospitalization in an analysis all individuals (n = 48,449) with IBD in the histology register.