Reply to Prof. Dorta’s Editorial

 

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We are grateful to Prof. Dorta for his critical appraisal of the gastroscopic breath test (GBT) [1] [2]. However, we do not agree to major points in the criticisms raised in the editorial.

GBT should not be misunderstood as a new principle for detecting Helicobacter pylori infection. The aim of the study was to describe the feasibility of a progressive, validated, and noninvasive technique for ¹³C-urea breath testing using continuous molecular correlation spectroscopy, providing real-time results, in a new clinical setting - i. e., during gastroscopy.

We are aware that in the study presented, strict criteria for contraindications to biopsy sampling were applied, including treatment with nonsteroidal anti-inflammatory drugs (NSAIDs). However, the two most recent recommendations from the American Society for Gastrointestinal Endoscopy (ASGE) are hardly evidence-based expert opinions, as they are based on very limited published data [3] [4]. In clinical reality, the use of aspirin, NSAIDs, and warfarin has been associated with significant upper and lower gastrointestinal bleeding [5] [6] [7] [8] [9] [10] [11], and many gastroenterologists would avoid taking biopsies in patients taking these medications. We agree that the risk of bleeding after biopsy may be relatively small, but the use of GBT for H. pylori testing can eliminate this avoidable risk in the large population undergoing endoscopy.

Most patients with an indication for H. pylori detection will in any case initially undergo an upper gastrointestinal endoscopy examination to evaluate related mucosal lesions; the test described by our group was designed for this group of patients alone. Thus, there is no additional risk of gastroscopy at all. In addition, the very small risk involved in diagnostic gastroscopy needs to be distinguished from the risks of H. pylori testing. On the other hand, gastroscopic breath testing will certainly not be used in patients who have already undergone endoscopic evaluation. The use of GBT therefore does not mean replacing a simple breath test with a gastroscopic procedure; instead, it combines two standard diagnostic tests that can be clinically performed simultaneously.

Furthermore, there are no reasons to expect that the validity of the breath test will be significantly altered by concomitant oxygen therapy, which is often administered during gastroscopy under conscious sedation. Since the detection of H. pylori is based on the ¹²C/¹³C ratio in the breath, not on the concentration of CO₂, we do not think that supplemental oxygen therapy during gastroscopy might be capable of affecting the results of the breath test. In addition, there are no data suggesting that H. pylori urease activity might be sensitive to inhaled oxygen to any clinically relevant extent.

It was not the aim of this feasibility study to provide an extensive economic analysis. This would require a larger number of patients and outcome data, which were both clearly beyond the scope of this study. However, the costs per test were included and compared with the overall costs, including the biopsy-based H. pylori urease test. As with most new methods, it is likely that the costs per test will decline further in the near future should continuous real-time breath testing come into more widespread use.

The breath test unit described is a mobile device that does not require fixed installation in a specific (endoscopy) room and can also be used in other locations. The test is usually carried out by the same nurse who prepares the endoscopic procedure. It is very easy to initiate, and once started, breath testing does not require constant monitoring; the device stops automatically. The procedure described can therefore easily be combined with a standard gastroscopy in the usual clinical setting.

It is of course possible to carry out a conventional urea breath test after a gastroscopy during which biopsies were not obtained. However, in clinical practice, this test is often carried out during a second visit, which is much less convenient for the patient and the medical staff, causing considerable additional time and costs. We pointed this out in our paper [2].

We believe that GBT is a valuable alternative approach to H. pylori testing, particularly in a selected group of patients who are undergoing gastroscopy but have contraindications to the acquisition of biopsies. The test results can be directly attached to the endoscopy report, facilitating administrative management and allowing immediate treatment decisions.

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M. Fried, M. D.

Division of Gastroenterology and Hepatology · University Hospital of Zurich

Raemistrasse 100 · 8091 Zurich · Switzerland

Fax: +41-1-255 4503

Email: michael.fried@usz.ch