Reviewer’ s report
Title: Effects of Endometriosis on Sleep Quality of Women: Does Life Style Factor Make a
Difference?
Version: 0Date: 07 Apr 2020
Reviewer: Christian Seitz
Reviewer's report:
Dear Authors,
your study addresses an interesting aspect of endometriosis and makes good use of the data thatwere collected. I would consider the paper suitable for publication if some revisions are made.
Major comments:
- With this study design it is possible to show associations/correlations but this does notnecessarily equal a causal relationship. This aspect needs to be clearly addressed in themethodology section, the discussion, and the conclusion. In several parts of the paper, the authorsconclude a causal relationship in a certain direction (e.g. lack of exercise results in more severeendometriosis) without discussing the opposite possibility (e.g. more severe endometriosis resultsin lack of exercise) or an association without causal relationship (e.g. a third known or unknownfactor influences both parameters). They even conclude on therapeutic interventions (recom-mendation to exercise) based on this incomplete and one-sided interpretation of the data.- The study reports numerous tests for statistical significance without addressing the issue ofmultiple testing and resulting alpha-inflation. This needs to be covered in both, the methodologysection and the discussion.
Minor comments:
- The purpose of the study is described inconsistently in different parts of the document (e.g. fulltitle vs. abstract vs. discussion). Please align.- line 46: giving a single number of prevalence of endometriosis seems inappropriate given thevariability across different studies- methods: please describe more clearly how the control group was selected, e.g. case matching?.It appears unlikely that the same number of patients in both groups occurred by chance if a randomseries of patients was included in the study.- methods: is there information on the reasons for infertility in the "healthy" controls?- line 83: "absence of stressful events" - infertility and the related treatment can probably beconsidered a stressful event by itself.- statistics: please add details on tested hypothesis, primary vs. secondary analysis, pre-definedstatistical analysis plan or retrospective analysis?, correction for multiple testing.- lines 152/153: wording of sentence is unclear- lines 154 ff: please discuss whether the factors that are associated with poor SQ are known to beassociated with poor SQ in non-endometriosis patients.- lines 171/172: ...or the findings show that women with endometriosis are less likely to exercise
(e.g. because of their pain, abnormal cycles, ...)
- lines 180/181: No, this was not shown by this study. This would require a longitudinal design.
- Table 1: p-value for age seems low when compared with the values. Please check.- Table 1: Line for BMI appears twice- Table 3: It would be interesting to see whether the same associations show up when more thantwo PSQI groups are analyzed, e.g. quartiles instead of "PSQI ≥5" and "PSQI < 5". Please
consider to add this analysis.
With best regards,
Christian Seitz
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
NoDoes the work include the necessary controls?
If not, please specify which controls are required in your comments to the authors.
YesAre the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
No
Are you able to assess any statistics in the manuscript or would you recommend an
additional statistical review?If an additional statistical review is recommended, please specify what aspects require furtherassessment in your comments to the editors.
I am able to assess the statisticsQuality of written English
Please indicate the quality of language in the manuscript:
Needs some language corrections before being publishedDeclaration of competing interests
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