Review for 10.1186/s12876-022-02520-6 (2022)

Title: Comparing Diagnostic Performance of Cantonese-Chinese version of Rome IV Criteria
and a short Reference Standard for Functional Dyspepsia in China
Version: 1 Date: 03 Jul 2022
Reviewer:  Sergius Onwukwe
Reviewer's report:
Comparing Diagnostic Performance of Cantonese-Chinese version of Rome IV Criteria and a
short Reference Standard for Functional Dyspepsia
Review comments
Participants and setting
1 The authors said, “we sampled dyspeptic patients consecutively from GI outpatient
departments of the Hong Kong Prince of Wales Hospital and the community”. This sentence
should be the prelude to the participants setting including a brief information about this setting,
population and number of patients that attends the outpatients of this study setting monthly or
yearly so as to inform the reader where the study was done including the study population.
Sample size
2 In the determination of the sample size used for this study, I could see that evidence was
provided for the sample size calculation, however, was provision made for non-response in terms
of those participants that may have decided not to continue to participate in the study? Usually,
in most cross-sectional studies there is always a need to make this provision because of the high
probability of drop outs or non-response after study samples are already determined and the
study commenced. This is also important as this study employed small sample size, and any
significant non-response rate would limit the sample size further and then make it more difficult
to generalize the findings even in the context of the study.
Ethics approval/permission to conduct study
3 In this section, it is important to include information on if preliminary permission was formally
sought and obtained from the hospital authorities where the research participants were recruited.
This is an important first step before ethics applications are given as most ethics committee will
not give research approval if this evidence is not included in the application process.
Data analysis
4 Which analytical tool and version was used for data analysis? This is a glaring omission. There
is also need to include information on why multivariate logistic regression analysis was not done
after the bivariate analysis. Is it due to the design of the study or the outcome that was being
expected in terms of comparing 2 diagnostic tools? This needs to be clearly explained.
Discussion
5 In the section on discussion, 2nd paragraph, 1st and 2nd sentences, I could see the effort that
was made in outlining the clinical consequences of not using the new tool this study is proposing
for diagnosing or ruling out FD such as unnecessary initiation of FD treatments, adverse events
associated with overtreatment of FD and its relation to evidence based on previous similar
studies.  However, this argument can be strengthened if it is also related to the socio-economic
consequences of not using this new tool including its evidence base so as to exhaust this aspect
of the discussion emanating from this study. For example, it is well known in clinical practice
that unnecessary initiation of treatments that does not confer any clinical benefit to patients’
results to economic and financial waste and increases more cost to the health care system which
is well rooted in evidence. I would like this aspect of the findings of this study as indicated above
to highlight and discuss this including its evidence base so as to strengthen the quality of this
study in relation this aspect of the discussion.
Limitations
6 The authors concluded that; “ the Reference Standard is capable of ruling out patients without
FD, PDS, or EPS. It can be used as a concise instrument for FD initial screening in routine
practice, especially in settings where the use of the Rome IV diagnostic instrument is not
practical”. While I agree with the authors on this based on your findings, however, a fundamental
possible limitation of this is that it may not be reliably generalized not only to the context of the
study but also, elsewhere. This is predicated on the fact that the sample size that was used to
generate the tool (the Reference Standard for ruling out patients without FD, PDS, or EPS) is
small, and is further limited by the fact that the data/patients were recruited consecutively. It is
important that we remember most statistical analysis assumes that data are collected randomly
and this is one of the important assumptions in generalizing findings especially from cross
sectional designs/studies. This should be clearly included as a limitation to this study so that
readers can put it into context while deciding how to apply the findings of the study.
7 Does this study have any strengths? and if yes, it needs to be included otherwise readers would
want to know why they should read the manuscript
Referencing
8 The authors are to ensure that the Vancouver referencing style as required in the publishing
guidelines for this journal is strictly followed in your referencing and include appropriate links
on how to retrieve the articles cited in the references where necessary.
Dr SC Onwukwe (Reviewer)
Department of Family Medicine, University of the Witwatersrand, South Africa