Background: We have developed a technique for measuring fecal excretion of human DNA by assuming that luminal desquamation of epithelial and inflammatory cells increases in damaged colonic mucosa. However, the clinical usefulness of this technique in the follow-up of patients with ulcerative colitis has not been established. The aim of this study was to determine the stability of fecal DNA in inactive ulcerative colitis and its potential value as an indicator of relapse.
Methods: The 54 patients with clinically quiescent ulcerative colitis in this prospective study were followed for 12 months or until clinical relapse (clinical activity index > 7). Fecal calprotectin concentration was determined by ELISA, and fecal DNA concentration was determined by quantitative PCR.
Results: During the year of follow-up, 23 of the 54 patients relapsed, with a median increase in the colitis activity index from 1.0 to 8.0 (P < 0.01). Median fecal DNA remained unchanged in patients with stable, inactive colitis, ranging from 6.8 copies/microg at inclusion to 1.7 copies/microg at the end of follow-up. Fecal calprotectin level also was unchanged, ranging from 414.0 microg/g at inclusion to 128.9 microg/g at the end of follow-up. In contrast, fecal DNA concentration increased significantly in patients who relapsed (259.0 versus 3.9 copies/microg at entry; P < 0.01). Similar increases in relapsing patients were also observed with fecal calprotectin. ROC curve analysis to assess the accuracy of fecal DNA and calprotectin in detecting relapses during follow-up yielded similar results.
Conclusions: Fecal DNA concentration remained stable in patients with inactive ulcerative colitis but increased significantly with relapses. Determining fecal DNA concentration may be a new objective instrument to use in the follow-up of patients.