Performance of common disease activity markers as a reflection of inflammatory burden in ulcerative colitis

Abstract

Background: The inflammatory burden influences therapeutic decisions in patients with ulcerative colitis (UC). We aimed to study which commonly used markers of disease activity correlate best with inflammatory burden in patients with UC using leukocyte scintigraphy (single-photon emission computed tomography [SPECT-CT]) as the gold standard. Methods: Patients with different severity of UC underwent colonoscopy with biopsies and leukocyte SPECT-CT scintigraphy. Serum C-reactive protein (CRP), fecal calprotectin, and clinical questionnaires were collected. The maximum uptake of technetium-labeled leukocytes was calculated as a SPECT score for each colon segment and a summed activity score for 5 colonic segments combined. Results: Thirty patients with UC were included; 14 of 30 (47%) had left-sided colitis, and 16 of 30 (53%) had pancolitis. One patient (3%) had inactive UC, 5 of 30 (17%) had mild, 11 of 30 (37%) had moderate, and 13 of 30 (43%) had severe disease activity based on the endoscopic Mayo score. The endoscopic Mayo score correlated better with the SPECT score than with the ulcerative colitis endoscopic index of severity (UCEIS) (r 0.50; P < 0.01 and r 0.32; P 0.08, respectively). The Geboes UC histologic score correlated equally well as the Mayo score (r 0.50; P < 0.01). We found a significant correlation between scintigraphy and fecal calprotectin (r 0.44; P 0.02) but not with serum CRP (r 0.25; P 0.18). Fecal calprotectin reflected inflammatory burden significantly better in left-sided colitis (r 0.80; P 0.001) than in pancolitis (r 0.22; P 0.41). Conclusions: The inflammatory burden in patients with UC, measured by SPECT-CT, is better reflected by the endoscopic Mayo score and the Geboes histologic score than by the UCEIS. Fecal calprotectin is a more accurate inflammatory marker than CRP, predominantly in patients with left-sided colitis.