Abstract
Background and Aim: The disease severity index (DSI) for inflammatory bowel disease (IBD) is a novel tool that encapsulates the burden of illness but requires endoscopic assessment. This study developed non-invasive DSIs using faecal calprotectin (DSI-fCal) and faecal myeloperoxidase (DSI-fMPO) instead of colonoscopy and investigated whether these indices were associated with the burden of disease.
Methods: Adults with Crohn’s disease (CD) and ulcerative colitis (UC) were recruited prospectively and followed for 24 months. Baseline biomarker concentrations were used to develop DSI-fCal and DSI-fMPO, and these were correlated with the original DSI, baseline IBD symptoms (Harvey-Bradshaw index for CD and simple clinical colitis activity index for UC), endoscopic activity (simple endoscopic score for CD and UC endoscopic index of severity), symptoms of stress (perceived stress scale-10), depression (patient health questionnaire-9), anxiety (generalised anxiety disorder scale), and quality-of-life (QoL; IBD questionnaire 32). Area under the receiver-operating-characteristics curves (AUROC) assessed baseline DSI-fCal/DSI-fMPO as predictors of incident clinical and biochemical remission at six months (symptom remission and fCal <150 μg/g), and a complicated IBD course at 24 months (disease relapse needing escalation of biologicals/immunomodulators/recurrent corticosteroids, IBD-hospitalisations/surgeries). Multivariable binary logistic regression assessed the utility of DSI-fCal/DSI-fMPO in predicting a complicated IBD course.
Results: In total, 171 patients were included (CD=99, female=90, median age=46y (IQR 36-59)). DSI-fCal and DSI-fMPO correlated with the original DSI (r>0.9, p<0.001), endoscopic indices (r=0.45-0.49, p<0.001), IBD-symptoms (r=0.53-0.58, p<0.001), stress (r=0.25-0.30, p<0.1), depression (r=0.32-0.35, p<0.001), anxiety (r=0.16-0.19, p<0.05), and QoL (r=-0.57—0.58, p<0.001). Baseline DSI-fCal (AUROC=0.79, 95% CI 0.65-0.92) and DSI-fMPO (AUROC=0.80, 95% CI 0.67-0.93) were associated with six month clinical and biochemical remission. DSI-fCal (AUROC=0.83, 95% CI 0.77-0.89) and DSI-fMPO (AUROC=0.80, 95% CI 0.73-0.87) performed similarly in predicting a complicated IBD-course to the original DSI (pdifference>0.05, Figure 1). The non-invasive DSIs were independently associated with a complicated IBD-course on multivariable analyses (DSI-fCal28, aOR=6.04, 95% CI 2.42-15.08; DSI-fMPO25, aOR=7.84, 95% CI 2.96-20.73).
Conclusion: The DSI-fCal and DSI-fMPO were significantly associated with the wide burden of IBD. These non-invasive DSIs performed similarly in prognosticating the longitudinal disease course as the original DSI, whilst avoiding a need for endoscopic assessment.