To Örebro University

Background: Faecal calprotectin, an established biomarker used to assess mucosal inflammation, has been shown to correlate with endoscopic activity in inflammatory bowel disease (IBD). Longitudinal monitoring of faecal calprotectin, however, has rarely been employed beyond assessment of therapy response and post hoc analyses of clinical trials.

Aim: To study whether consecutive measurements of faecal calprotectin every third month are useful for monitoring patients with IBD in clinical remission.

Methods: Patients aged 18 years or older, with a known diagnosis of IBD in clinical remission, were prospectively studied. Patients provided faecal samples every third month and were prospectively followed until the first clinical relapse or the end of the 2-year follow-up period. Measurements (EK-CAL, Bühlmann Lab. AG, Switzerland) were done at the end of the study. A Cox model with time-dependent covariates was used for analysis.

Results: Among 104 patients, Crohn's disease (n = 49) and ulcerative colitis (n = 55), 37 had a relapse. A doubling of faecal calprotectin level between two consecutively collected samples was associated with a 101% increased risk of relapse (HR: 2.01; 95% CI: 1.53-2.65; P < 0.001). The relative risk of relapse attenuated with time (HR: 0.80; 95% CI: 0.75-0.86; P < 0.001), by a 20% decrease in risk of relapse per 3-month period since the sample was obtained.

Conclusions: By consecutively measuring faecal calprotectin every third month, we quantified the risk of relapse related to faecal calprotectin change and observed attenuation of the risk across time. Our data suggest that longitudinal monitoring of faecal calprotectin is informative in predicting relapse in IBD.