A large study (WJ Sandborn et al Gastroenterol 2016; 150: 96-102) focuses on the question of how well calprotectin values correlate with clinical outcomes. As part of a double-blind, placebo-controlled phase 2 trial of 194 patients who received various doses of tofacitinib or placebo, the authors obtained data on fecal calprotectin (FCP). Here were the key findings:
- Week 8 FCP levels were significantly lower in those with a clinical response: 156 vs 725 mg/kg, in clinical remission: 64 vs 617 mg/kg, in endoscopic remission: 44 vs 489 mg/kg and in mucosal healing: 127 vs. 753 mg/kg.
- On an individual level, FCP showed only moderate agreement for these measures.
For clinical remission, FCP concentration:
- At 50 mg/kg, the specificity was 0.91, sensitivity was 0.43
- At 150 mg/kg, the specificity was 0.79, sensitivity was 0.68
For endoscopic remission, FCP concentration:
- At 50 mg/kg, the specificity was 0.88, sensitivity was 0.52
- At 150 mg/kg, the specificity was 0.75, sensitivity was 0.79
For mucosal healing, FCP concentration:
- At 50 mg/kg, the specificity was 0.92, sensitivity was 0.29
- At 150 mg/kg, the specificity was 0.85, sensitivity was 0.54
The authors speculate that the only fair to good accuracy of FCP in classifying clinical and endoscopic outcomes of individual patients could be related to day-to-day variability in FCP levels and due to residual microscopic inflammation.
My take: While a single normal calprotectin value is not entirely reassuring, I would not be surprised if these values outperform the PGA (physician global assessment). It is likely that serial calprotectin values will be helpful in tracking clinical progress.
Agardh et al. JPGN 2016; 62: 43-46. Authors show that fecal calprotectin levels were markedly elevated (median 844 mg/kg) in 11 of 12 patients with juvenile polyps and that these levels normalized after polypectomy. These levels were similar to their cohort (n=129) of children with active IBD (median values of 962 mg/kg).
Heida et al. JPGN 2016; 62: 47-49. The investigators retrospectively examined 80 children who had endoscopy due to suspected inflammatory bowel disease. In all 10 of the children with calprotectin levels less than 50 (mcg/g), IBD was excluded.
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