Review for 10.1186/s12876-023-02777-5 (2023)

Title: Establishing Minimal Clinically Important Differences for the Quality of Life Instrument
of Chronic Gastritis QLICD-CG(V2.0) Based on Distribution-Based Methods
Version: 2 Date: 15 Jan 2023
Reviewer's report:
General Comments.
Calculating MCID values is very important to increase the usability of measurement instruments
developed for PRO studies in clinical practice, and it is of great benefit in integrating the PRO
approach into clinical practice. So this study is promising one for this purpose. It would be
appropriate to remove the important uncertainties that I have identified in the research setup and
the evaluation of the results. These are mentioned below. Please consider.
Introduction:
Very satisfactory
Methods:
1-The way describing the methods calculating MCID are very theoretical. So, how the minimum
clinically significant difference is calculated by applying the anchor-based model and the
distribution based models should be illustrated in more detail by giving  examples in the
methods section. The reader should understand the methods done very briefly. For example
when calculating anchor based approach correlations “the correlations between Q1 item and
each domain score” were reported to be done in the results section. Please clarify very briefly
in the methods section as well, together on the examples of calculation.
As for the distribution methods, the formulas given in table one are very complex and needs
clarification for the readers.
2-Please also describe why they used Q1 of the SF-36 instead of Q2 (health transient item of the
SF-36) when calculating Anchor Based MCID (as usually done?).
Results
3-In the Resulst section, the reader was directed only to the tables for the MCID values calculated
in the anchor and distribution-based approaches, and no findings were given verbally in the text.
MDCID findings in the tables must be given in the text as well.
4-The comparison of the MCID values obtained by different methods (either Anchor based or
Distribution based) are laking in the results section. The MCID values should be collected in
a single summary table including all of the MCID values obtained by all the methods used
(including that of obtained by Anchor based method) in the study. This allows readers to evaluate
the MCID values calculated by all methods together.
5-The most important shortcoming of the analyzes of this study is that the MCID values
calculated with the Anchor-based approach were not compared with the distribution-based
MCID values by statistical methods. In the discussion section, these comparisons are made
only with subjective criteria such as "closeness / distance". It is important to make statistical
comparisons.
Discussion
6-Why did the authors took “maximum effect “ when comparing anchor and distribution
methods? Why not using “medium” method?
7-If the Anchor based method was taken as “gold standard”, then why did the authors conclude
the MCID values obtained by (1.96) SEM approach which is a distribution based methods. Are
the  values obtained by a distribution method is more robust that Anchor based values? Why not
suggest MCID obtained by Anchor based method (it its really a gold standard)?
8-In the discussion, it was also possible to present which of the distribution-based MCID
calculation methods generally gave closer results compared to the anchor-based results. Not only
for studies conducted with this scale, but also for other scales whose MCID values are calculated
in the literature. (just one given: Crohn’s disease [33]). More others please.
9-In table 3 the number of cases are mentioned as “101”. Why not the entire study population
(157)?
10-Conclusion section should write in a more concrete way. Just give recommendations based
on your concrete findings.