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P224. Exhaled pentane may identify disease activity in patients with inflammatory bowel diseases

M. Bortlik1, K. Dryahina2, D. Duricova1, N. Machkova1, P. Spanel2, M. Lukas1, 1ISCARE and Charles University, IBD Clinical and Research Centre, Prague, Czech Republic, 2J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic

Background

The current diagnostic methods used for assessment of disease activity in patients with ulcerative colitis (UC) and Crohn's disease (CD) are either invasive, or have limited sensitivity and specificity. Among biological markers, C-reactive protein (CRP) and faecal calprotectin (FC) are most frequently used for this purpose. However, identification of new sensitive and non-invasive biomarkers may be of great value in routine clinical practice.

Methods

One hundred and eighty patients with inflammatory bowel diseases (IBD; 129 CD and 51 UC) were recruited and participated in an ongoing study. Clinical activity indices [Harvey–Bradshaw (HB) and Simple Clinical Colitis Activity Index (SCCAI)], biological markers (CRP, FC), and colonoscopy were used for assessment of disease aktivity. Patients were divided into 3 groups: complete remission (G1), partial remission (G2), and disease activity (G3). Fourteen volatile organic compounds (VOCs) were quantified in the exhaled breath of all patients using selected ion flow tube mass spectrometry (SIFT-MS), and results (expressed in parts per billion by volume; ppbv) in each group were compared.

Results

Among all VOCs assessed, pentane concentrations in G1 and G3 were significantly different: median concentrations in CD patients were 51 ppbv (range: 29–86), and 37 ppbv (18–68) in G1 and G3, respectively. In UC patients, concentrations were 57 ppbv (41–88), and 39 ppbv (21–54) in G1 and G3, respectively. Significant correlation of exhaled pentane concentration with HBI/SCCAI was observed (Pearson correlation coefficient p = 0.41 for CD, and 0.46 for UC, resp.). Exhaled pentane also showed good sensitivity and specificity as a marker of disease activity (AUC 0.776 for CD and 0.837 for UC patients). The median values of other VOCs were not significantly different.

Conclusion

Pentane concentrations in exhaled breath of IBD patients correlate with disease activity, and may help to differentiate between patients with active and non-active disease.

This work was supported by IBD-Comfort Foundation.