Figure 1

Performance of the hydrogen breath tests at different hydrogen cut-offs. Percentage of positive, negative and borderline hydrogen breath test results by three different hydrogen breath cut-offs as indicated. An increase in the production of hydrogen ≥20 (≥15; ≥25) ppm and a two-fold increase of the individual baseline H₂-exhalation in three consecutive breath samples was considered positive. Breath test, in which three hydrogen values were ≥20 (≥15; ≥25) ppm but not all of those topped the baseline value by a two-fold increase or where hydrogen levels reached at least 20 (≥15; ≥25) ppm but not at three time points were considered as borderline. All other test results were classified as being negative.