QUALITY-CONTROL STUDY OF H-2 BREATH TESTING FOR THE DIAGNOSIS OF CARBOHYDRATE MALABSORPTION IN ITALY

Background and Aims. H-2 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 H-2 brea th testing methods and to design the quality control study. Fifteen ou t of 23 laboratories responded to the questionnaire and 12/23 complete d the entire study. Results, The survey revealed that a large variety of H-2 testing methods are employed in Italy, but none have been previ ously tested for accuracy. This prospective study showed that these te sts fail to identify > 20% of patients with malabsorption. In contrast , a new method based on single H-2 breath measurement at 6 hours after lactulose ingestion and a cutoff value of greater than 5 ppm, had a s ensitivity 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 s pecificity of 100%. This improved accuracy was obtained with a much si mpler testing procedure in which only one breath sample is analyzed in contrast to the baseline and multiple subsequent samples that are ana lyzed using the currently employed techniques. Conclusions. A great im provement in the accuracy of the H-2 breath test, as well as a conside rable saving in terms of time and costs, may be possible through the u se of a new, simplified H-2 breath test followed by careful H-2 analys is.