Review for 10.1186/s12876-021-02028-5 (2021)

Reviewer’s report
Title: 
The LUCID study: Living with Ulcerative Colitis; Identifying the
socioeconomic burden in Europe
Version: 
0 
Date: 
26 Mar 2021
Reviewer's report:
In this paper, the authors aimed to study annual costs of living with UC from a
societal perspective, and the effects of some PROMS on UC.
the study is interesting, but needs additional explanations on some major points.
MAIN COMMENTS.
Introduction.
The introduction is well-written, but I have some comments on the content. I
would suggest to report information on medications in a fair way. This means
that the specific mention of Tofacitinib should be deleted.
In the same meaning, reference 2 already included recommendations on Tofa, as
well as the reference 12. Therefore, this last should be deleted from the reference
list, unless all papers on other treatments are fairly considered separately too.
References 18 and 19 are focused on healthcare costs, which I don't understand
the link with your paragraph.
I did not understand what was meant by "active UC". UC is a chronic disease,
and the impact on patients life is largely due to the chronic component, that
cannot disconnect active and remission phases. PLease explain.
Assessing the impact - as compared to the effect - of UC on the factors
mentioned would have asked for another study design than a cross-sectional one.
Please update this term on page 6.
Methods.
Please refer to the STROBE checklist for observational studies when describing
the methods, including paragraphs ordering. An non-interventional study is
observational.
Overall, the description of the methods is largerly unordered - therefore difficult
to follow.
Some examples where more explanation is needed.:
- I did not found a clear definition of the index date. 
- How did you include patients in ARM2? what was the time lag considered
between the moderate or severe UC status and the remission obtained? this
means that your observation period started before 12 months? Were moderate-
severe episodes the first experienced by patients or any other?
- It is not clear how did patients agree their data to be collected for the study. Did
they sign an ICF - if yes, how did you manage ICFs in all local languages? If
only those that understood English were selected, means a clear study bias.
- How were detailed information on costs collected? Could you give an example
(for example related to direct costs - for example regarding use of infliximab -
and how you handled differences by countries)
- statistical details are missing regarding analyses performed to answer study
objectives. Here the paragraph only refers on how data on costs were built.
Results.
- lines 14-15 and 42 (page 11): some kind of same information is reported, but
95% patient response rate first is attributed to Spain, second to Romania. Please
check your results.
- up to 12% (10%) of UC patients had strictures or fistulas. Does this mean that
diagnosis of UC was not ascertained the same in each country? or may have
changed to CD. PLease comment.
- differences according to countries are sometimes based on very low numbers,
which is a clear limit to generalisation of the results for those countries.
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
No
Are the methods sufficiently described to allow the study to be repeated?
No
Is the use of statistics and treatment of uncertainties appropriate?
No
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes