FC reliability across UC

April 22, 2025

Issue 08

Clinical Question

Does disease extent affect fecal calprotectin’s accuracy in UC?

Editor’s Bottom Line

Although fecal calprotectin elevation is attenuated in patients with more distal ulcerative colitis, it continues to perform well as a biomarker for active disease.

Reference

Steinsbø Ø, Aasprong OG, Aabakken L, et al. Fecal Calprotectin Correlates with Disease Extent but Remains a Reliable Marker of Mucosal Healing in Ulcerative Colitis. Am J Gastroenterol. Epub ahead of print Jan 30, 2025; https://journals.lww.com/ajg/fulltext.aspx

Synopsis

This single-center observational study investigated the relationships between fecal calprotectin (FC), mucosal inflammatory activity and disease extent in ulcerative colitis (UC), along with assessing how disease extent affects FC’s diagnostic accuracy.

The researchers analyzed data from 518 visits by 254 patients with UC treated between 2014 and 2024 at Stavanger University Hospital, Norway. The study population included 144 females (56.7%) and 110 males (43.3%), with a mean age of 38 years (range: 18–80). Among the 518 total visits, 199 were at diagnosis and 319 were follow-up visits during treatment.

Endoscopic disease extent was classified as proctitis (162 visits, 31.3%), left-sided colitis (172 visits, 33.2%), and pancolitis (184 visits, 35.5%). The median Mayo Endoscopic Score (MES) was 2 (interquartile range [IQR] 1-2), with 262 visits showing endoscopic activity (MES ≥2). The median Nancy Histological Index (NHI) was 2 (IQR 1-3), with histologic activity present (NHI ≥2) in 326 visits.

Results showed that median FC levels increased with disease extent and were significantly higher in active inflammation. In patients with endoscopically active UC (MES ≥2), FC levels were significantly lower in the presence of proctitis (440 mg/kg), compared to left-sided colitis (840 mg/kg, p=0.048) and pancolitis (1,690 mg/kg, p=0.00005). Similarly, in patients with mild or no endoscopic activity (MES ≤1), FC levels were significantly higher in the presence of pancolitis (85 mg/kg) than in proctitis (24 mg/kg, p=0.00032) or left-sided colitis (40 mg/kg, p=0.012).

Despite these differences, FC remained a reliable marker for mucosal healing across all disease extents, with area under the receiver-operating characteristic curve (AUROC) ranging from 0.878 to 0.915, and no significant differences between extent categories (p≥0.2919). The optimal FC cutoff for detecting mucosal healing was 161.5 mg/kg, with a sensitivity and specificity of 0.795 and 0.912, respectively.

Details

Study Design: Observational study
Funding: Unrestricted grants from AbbVie and Tillotts Pharma
Allocation: None
Setting: Single-center
Level of Evidence: 2b