The utility of serum anti-tumour necrosis factor levels and biomarkers in predicting endoscopic activity in inflammatory bowel disease

Abstract

Introduction: Although higher anti-tumour necrosis factor (anti-TNF) levels are associated with higher rates of clinical remission, much less is known regarding the associations between biomarkers and endoscopic findings in patients with inflammatory bowel disease (IBD). Methods & methods: A retrospective analysis of patients with available anti-TNF levels attending an IBD clinic at a tertiary centre from 1st January 2014 – 31st May 2020 was completed. Demographics, disease activity scores, endoscopic findings and biomarker data were collected. The area-under-curve (AUC) on the receiver operating characteristic curve was plotted to measure and compare the performance of variables in predicting endoscopic remission. This was supplemented by linear discriminant analysis. Results: One hundred and eighty patients were included. Faecal calprotectin was better at distinguishing between quiescent and active endoscopic disease than anti-TNF level .AUC 0.78 (95% CI 0.68 – 0.89) versus 0.62 (95% CI 0.48 – 0.75). Faecal calprotectin had a higher sensitivity (77% vs 50%) and specificity (71% vs 64%) compared to anti TNF levels in predicting endoscopic activity. We found that a faecal calprotectin threshold of 200ug/g and similarly an anti TNF level of 6.21ug/ml optimally predicts endoscopic disease. Using linear discriminant analysis, faecal calprotectin was weighted against C-reactive protein (CRP), albumin, platelet count, anti-TNF, and has shown to be better at predicting mild to moderate disease activity (Log FC=0.74). Conclusion: Faecal calprotectin as opposed to anti-TNF level is more likely to predict endoscopic disease activity. We plan to do a prospective study to confirm these findings and to develop a set of clinical cut-offs to improve disease management.