Quality control study of H2 breath testing for the diagnosis of carbohydrate malabsorption in Italy. The "Tenue Club" Group.

BACKGROUND AND AIMS: H2 breath testing is increasingly used in Italy. The aim of this multicenter study was to assess the accuracy of this technique in the diagnosis of carbohydrate malabsorption. METHODS: An anonymous questionnaire was used to collect information about H2 breath testing methods and to design the quality control study. Fifteen out of 23 laboratories responded to the questionnaire and 12/23 completed the entire study. RESULTS: The survey revealed that a large variety of H2 testing methods are employed in Italy, but none have been previously tested for accuracy. This prospective study showed that these tests fail to identify > 20% of patients with malabsorption. In contrast, a new method based on single H2 breath measurement at 6 hours after lactulose ingestion and a cutoff value of greater than 5 ppm, had a sensitivity of 92% +/- 4% and a specificity of 94% +/- 0.5%. Increasing the cut-off to 10 ppm resulted in a sensitivity of 88% +/- 9% and a specificity of 100%. This improved accuracy was obtained with a much simpler testing procedure in which only one breath sample is analyzed, in contrast to the baseline and multiple subsequent samples that are analyzed using the currently employed techniques. CONCLUSIONS: A great improvement in the accuracy of the H2 breath test, as well as a considerable saving in terms of time and costs, may be possible through the use of a new, simplified H2 breath test followed by careful H2 analysis.