P411 Faecal calprotectin is more tightly associated with endoscopic disease activity compared with other biomarkers in patients with inflammatory bowel disease under maintenance treatment with adalimumab

E. Orfanoudaki, E. Theodoraki, K. Foteinogianopoulou, A. Mantaka, I. Koutroubakis

Gastroenterology, University Hospital of Heraklion, Heraklion Crete, Greece

Background

Fecal calprotectin (FC) has been suggested as an important biomarker for the management of patients with inflammatory bowel disease (IBD). It is an indirect index of disease activity and plays a crucial role in the treat-to-target strategy. Consecutive measurements of FC in patients in clinical remission can predict a disease relapse and lead to early treatment optimisation. We aimed to compare FC with other biomarkers as for their association with endoscopic activity in IBD patients under maintenance treatment with adalimumab.

Methods

Consecutive IBD patients under maintenance treatment with adalimumab were studied retrospectively based on prospectively recorded data in an IBD registry. Inclusion criteria were at least one available endoscopic evaluation with accompanied biomarkers measurement within the last ± 3 months in the study period (10/2016–9/2019). Biomarkers assessed were FC (home testing Βühlmann fCAL ELISA), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), haemoglobin (Hb), white blood cells (WBC) and platelets (PLT). The disease was considered as active if endoscopic Mayo score was ≥2 in ulcerative colitis (UC) and SES-CD score >6 for Crohn’s disease (CD).

Results

From a total of 72 IBD patients under maintenance treatment with adalimumab, 53 met inclusion criteria [49 CD, 32 men, mean age 42.3 ± 14.9 years, mean disease duration 13.4 ± 9.5, median adalimumab use 34 (23–65) months, combination with immunosuppressants 11 (22%)]. In the logistic regression analysis with dependent variable, the endoscopic active disease FC (mean value 470.8 ± 382.3μg/g) and ESR were independently significantly correlated with the endoscopic disease activity (OR:1.002 95% CI 1.001–1006, p = 0.003 and OR:1.05 95% CI 0.01–1010, p = 0.01 respectively). FC identified patients with endoscopic active disease with an area under the receiver operating characteristic curve (AUC) value of 0.78 (95% CI 0.64–0.88) higher than the other biomarkers [CRP, AUC 0.70 95% CI 0.56–0.82; Hb, AUC 0.55 95% CI 0.41–0.69; ESR, AUC 0.57 95% CI 0.43–0.71; PLT, AUC 0.56 95% CI 0.42–0.69 and WBC, AUC 0.43 95% CI 0.35–0.63). In the pairwise comparison of the ROC curves, there was a significant difference of the AUC of FC and the AUC of Hb, ESR, PLT and WBC (all with p < 0.05). There was no significant difference between the AUC of FC and that of CRP (p = 0.35). FC levels >413 μg/g had a sensitivity of 75% and a specificity of 76% in predicting endoscopic active disease.

Conclusion

These real-life results indicate that in IBD patients under maintenance treatment with adalimumab faecal calprotectin home testing performs better than the other biomarkers in predicting the disease endoscopic activity.