Title: Validity of rapid urease test using swab of gastric mucus to mucosal forceps and 13C-
urease breath test: a multicenter prospective observational study
Version: 1 Date: 22 May 2024
Reviewer's report:
In this multicenter prospective study, the authors compared the diagnostic performance of the
rapid urease test (RUT) using gastric wall swabs (Swab-RUT) and conventional RUT for the
diagnosis of H. pylori infection. Swab-RUT showed high sensitivity, specificity, and accuracy
for diagnosing H. pylori infection, suggesting the usefulness of a less-invasive Swab-RUT.
There are some important considerations.
Major
1. A total of 94 patients were enrolled in this study. However, only 41 patients underwent forceps
RUT and Swab-RUT simultaneously. Since the purpose of this study was to compare diagnostic
performance of Swab-RUT and conventional RUT, it would be reasonable to include 41 patients
who underwent both tests upon suspicion of H. pylori infection during endoscopic examination.
2. How was the number of subjects needed to assess the diagnostic performance of Swab-RUT
estimated?
3.  What is diagnostic criteria for diagnosing H. pylori infection in this study? In general, if
multiple tests are performed, a positive result from one of the tests is considered positive for H.
pylori infection, and a negative result from all tests is considered negative for the infection. This
study found that 5 cases were RUT positive but UBT negative. Are these cases positive for H.
pylori infection (UBT false negative) or not (Swab-RUT false positive)?
Minor
1. In this study, only 30 cases (31.9%) showed positive result to urea breath test (UBT). Indeed,
more than half of patients (53 of 94) were not expected to have H. pylori infection based on
Kyoto classification.
2. Although methods were not identical at all institution, detailed description of the cotton swab
preparation protocol and specimen collection methods would be informative (i.e., recommended
number of mucosal sweeping).
3. In this study, specimens for Swab-RUT and forceps RUT were obtained from gastric antrum
and corpus and interpreted separately. What about diagnostic performance of Swab-RUT based
on the location in the stomach?
4. It appears that both pronase and sodium bicarbonate were often used during endoscopic
examination in this study. This means that the effect of pronase or sodium bicarbonate on Swab-
RUT cannot be estimated separately.
5. Although subtle, sensitivity and positive predictive value were lower when using pronate or
sodium bicarbonate.
6. How did you grasp a 1 mm sized cotton swab with forceps and sweep the gastric mucosa?
7. Reference number 3 does not seem to be literature that supports the content described.
Title: Validity of rapid urease test using swab of gastric mucus to mucosal forceps and 13C-
urease breath test: a multicenter prospective observational study
Version: 1 Date: 22 May 2024
Reviewer's report:
In this multicenter prospective study, the authors compared the diagnostic performance of the
rapid urease test (RUT) using gastric wall swabs (Swab-RUT) and conventional RUT for the
diagnosis of H. pylori infection. Swab-RUT showed high sensitivity, specificity, and accuracy
for diagnosing H. pylori infection, suggesting the usefulness of a less-invasive Swab-RUT.
There are some important considerations.
Major
1. A total of 94 patients were enrolled in this study. However, only 41 patients underwent forceps
RUT and Swab-RUT simultaneously. Since the purpose of this study was to compare diagnostic
performance of Swab-RUT and conventional RUT, it would be reasonable to include 41 patients
who underwent both tests upon suspicion of H. pylori infection during endoscopic examination.
2. How was the number of subjects needed to assess the diagnostic performance of Swab-RUT
estimated?
3.  What is diagnostic criteria for diagnosing H. pylori infection in this study? In general, if
multiple tests are performed, a positive result from one of the tests is considered positive for H.
pylori infection, and a negative result from all tests is considered negative for the infection. This
study found that 5 cases were RUT positive but UBT negative. Are these cases positive for H.
pylori infection (UBT false negative) or not (Swab-RUT false positive)?
Minor
1. In this study, only 30 cases (31.9%) showed positive result to urea breath test (UBT). Indeed,
more than half of patients (53 of 94) were not expected to have H. pylori infection based on
Kyoto classification.
2. Although methods were not identical at all institution, detailed description of the cotton swab
preparation protocol and specimen collection methods would be informative (i.e., recommended
number of mucosal sweeping).
3. In this study, specimens for Swab-RUT and forceps RUT were obtained from gastric antrum
and corpus and interpreted separately. What about diagnostic performance of Swab-RUT based
on the location in the stomach?
4. It appears that both pronase and sodium bicarbonate were often used during endoscopic
examination in this study. This means that the effect of pronase or sodium bicarbonate on Swab-
RUT cannot be estimated separately.
5. Although subtle, sensitivity and positive predictive value were lower when using pronate or
sodium bicarbonate.
6. How did you grasp a 1 mm sized cotton swab with forceps and sweep the gastric mucosa?
7. Reference number 3 does not seem to be literature that supports the content described.
Please review this paper.
user
Title: Validity of rapid urease test using swab of gastric mucus to mucosal forceps and 13C-
urease breath test: a multicenter prospective observational study
Version: 1 Date: 22 May 2024
Reviewer's report:
In this multicenter prospective study, the authors compared the diagnostic performance of the
rapid urease test (RUT) using gastric wall swabs (Swab-RUT) and conventional RUT for the
diagnosis of H. pylori infection. Swab-RUT showed high sensitivity, specificity, and accuracy
for diagnosing H. pylori infection, suggesting the usefulness of a less-invasive Swab-RUT.
There are some important considerations.
Major
1. A total of 94 patients were enrolled in this study. However, only 41 patients underwent forceps
RUT and Swab-RUT simultaneously. Since the purpose of this study was to compare diagnostic
performance of Swab-RUT and conventional RUT, it would be reasonable to include 41 patients
who underwent both tests upon suspicion of H. pylori infection during endoscopic examination.
2. How was the number of subjects needed to assess the diagnostic performance of Swab-RUT
estimated?
3.  What is diagnostic criteria for diagnosing H. pylori infection in this study? In general, if
multiple tests are performed, a positive result from one of the tests is considered positive for H.
pylori infection, and a negative result from all tests is considered negative for the infection. This
study found that 5 cases were RUT positive but UBT negative. Are these cases positive for H.
pylori infection (UBT false negative) or not (Swab-RUT false positive)?
Minor
1. In this study, only 30 cases (31.9%) showed positive result to urea breath test (UBT). Indeed,
more than half of patients (53 of 94) were not expected to have H. pylori infection based on
Kyoto classification.
2. Although methods were not identical at all institution, detailed description of the cotton swab
preparation protocol and specimen collection methods would be informative (i.e., recommended
number of mucosal sweeping).
3. In this study, specimens for Swab-RUT and forceps RUT were obtained from gastric antrum
and corpus and interpreted separately. What about diagnostic performance of Swab-RUT based
on the location in the stomach?
4. It appears that both pronase and sodium bicarbonate were often used during endoscopic
examination in this study. This means that the effect of pronase or sodium bicarbonate on Swab-
RUT cannot be estimated separately.
5. Although subtle, sensitivity and positive predictive value were lower when using pronate or
sodium bicarbonate.
6. How did you grasp a 1 mm sized cotton swab with forceps and sweep the gastric mucosa?
7. Reference number 3 does not seem to be literature that supports the content described.
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