Review for 10.1186/s12876-019-1095-9 (2019)

Reviewer ’s report  
 
Title: Indirect costs associated with Ulcerative colitis: a systematic literature review of real -
world data 
 
Version: 0 Date: 26 Jul 2019  
 
Reviewer: Tero Ylisaukko -Oja 
 
Reviewer's report:  
 
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This article is a systematic literature review, which assesses indirect costs of ulcerative colitis. 
The topic is important but very difficult to analyze. There is limited original data available for 
the review and therefore, the conclusions from this review should be critically evaluated.  
 
 
Major comments:  
 
1) The authors compare costs of absenteeism, presenteeism, and productivity losses in moderate 
to severe UC across different populations. The costs wer e adjusted to 2017 currency values 
(USD). However, it is very difficult to compare indirect costs across different populations, when 
there are major differences in the societies and the overall costs levels. Also, there are different 
inclusion criteria (di sease severity, disease history) in the original articles, which makes 
comparing results across the studies difficult.  These issues should be discussed in more detail in 
the article.  
 
 
2) Data sources include some abstract -level data (Cannon et al. 2011, Katz Avitan et al. 2016, 
Hellström et al. 2017, Neovius et al. 2010). I would recommend not to use data from abstracts in 
the analyses because they commonly present preliminary and/or incomplete results. Also, there is 
typically limited information of the study sample and methodology in the abstracts. I would 
recommend removing abstract data from the analyses.  
 
 
3) There is limited discussion of the results. Please revise, expand and focus on the results 
specifically from this analysis.  
 
 
Minor comments:  
1) Please revise references 1, 28, 30, 31.  
 
2) The authors state that "Therefore, the objective of this SLR was to understand the impact of 
UC on indirect costs and resource utilization". To my understanding, resource utilization was not 
analyzed.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please speci fy what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
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1. Have you in the past five years received reimbursements, f ees, funding, or salary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation t hat may in any way gain or 
lose financially from the publication of this manuscript, either now or in the 
future?  
 
3. Do you hold or are you currently applying for any patents relating to the c ontent 
of the manuscript?  
4. Have you received reimbursements, fees, funding, or salary from an organization 
that holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have  no competing interests' 
below. If your reply is yes to any, please give details below.  
 
No financial competing inter ests 
 
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