Review for 10.1186/1471-230X-13-7 (2013)

Reviewer's report
Title:Evaluation of a new fluorescence quantitative PCR test for diagnosing
Helicobacter pylori infection in children
Version: 1Date:10 September 2012
Reviewer: Thomas Wex
Reviewer's report:
The manuscript addresses a relevant topic, even novelty is limited. However,
there are some shortcomings in the presentation of data and statistical analysis
that need to be addressed.
Major issues:
- Evaluation of a new technology for diagnostics requires an appropriate “gold
standard” to get fair and realistic characterization concerning sensitivity and
specificity. The authors applied the approach “any of two positive test” for an H.
pylori-positive status – this is reasonable. However, assigning the remaining
patients to the “H. pylori-negative group” is not possible and useful. In order to
prove the specificity, the patients need to be negative in all tests performed. As it
is now, the H. pylori-negative group includes also those with a single positive
RUT or 13C UBT. These patients should not be included since their “true H.
pylori-status” is unknown.
The statistics should be reassessed after new stratification.
- The authors mentioned that the established the new assay (page 5) and
corresponding results concerning controls (page 11). The information needs to
be presented in detail, since it is the only “proof” for the technical accuracy of the
assay available.
- The study design describes the inclusion of 138 consecutive patinets, but later
on exclusion criteria are listed. This does not fit. Either the 138 cases were
selected from a larger cohort (which need to be clinically characterized) or the
number of samples should be much smaller than 138.
- The tests (UBT and RUT) are performed in very insensitive manner. Usually
DOB > 3.0 (BUT) and reading of RUT (up to 24h) is used in most laboratories to
establish a “H. pylori-positive” status. This might lead to a reduced sensitivity of
the “gold standard” and artificially boost the accuracy of the PCR-based test. The
authors need to discuss this issue.
- The additional analysis concerning the age prevalence is not solid. If 138
samples are “distributed” to 6 groups, and the overall prevalence of the infection
is 1/3, each subgroup is based on few samples only. Therefore, no conclusion
can be drawn from these data.
- Table 2 should also include the mfqPCR as column in regard to the gold
standard.
- Discussion needs to be revised to limit the strength of conclusions (see also
comments above). The strong statement in abstract and discussion (about the
quality/accuracy) of the new test is not supported by data, and needs to be
discussed more critically. As stated in the last sentence, more prospective
studies are required to establish the new methodology in context to the routine
setting. But I don’t think that PCR alone will be the “gold standard” in future.
Minor Issues:
- Replace x rpm by x g, since rpm is only useful if diameter of rotor and type of
centrifuge is presented as well.
- Check for typos (e.g. fluorescent, antagonist) and format issues in literature
- The current study by of Belda et al. could be included in the discussion (PMID:
22921814)
- Which data were analyzed by ANOVA test?
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
'I declare that I have no competing interests'