Reviewer’ s report
Title: Psychometric evaluation of the Swedish version of the 30-Item Endometriosis Health
Profile (EHP-30)
Version: 0Date: 16 May 2020
Reviewer's report:
The authors are to be commended for submitting this well-written description of the psychometric
properties of the Swedish version of the EHP-30. They establish a good rationale for the need fordisease specific HRQoL measures for disorders with substantial psychosocial impacts suchendometriosis. The study methods are sound, the analyses appropriate and the conclusions arereasonable.
The required sample size calculations for planned test-retest and factor analysis are clearly
reported. While the n=120 required for the factor analysis was achieved, the sample size felt shortof the desired n=50 for the test-retest analysis (only 42 included in analysis of the 70 who returneda 2nd questionnaire). While the relatively low participation rate is acknowledged in the discussion(page 8, lines 35-37), could the authors please make further comment including on the possibleimpact of the shortfall (e.g. is the participation rate in line with other studies? What bias mightresult from the small numbers in the test-retest group?)? Regarding other studies, I note that whileUK, US, Dutch, French, Chinese and Portuguese studies are referenced, an Australian study hasbeen omitted (Khong SY et al. Is the 30-item Endometriosis Health Profile (EHP-30) suitable as aself-report health status instrument for clinical trials? Fertil Steril. 2010; 94:1928-32.).
In the discussion, the declines in subscale scores over time ("the differences between the two
measurements") are described as "not statistically significant" (page 8, lines 18-19). How this
analysis was conducted is not described in the methods (authors describe using ICC for test-retestreliability, but not how score differences were ascertained), nor are the results for analyses of scoredifferences reported. Could the authors please also include the 95% confidence intervals for theICCs (page 7, line 3)?
There is need for improved clarity/consistency around the reporting of the factor analysis results.
Abstract and the results (page 6, lines 23-24) states: "Factor analysis could roughly confirm threeof the five subscales". Yet on page 8, lines 45-46, "roughly confirmed the five-factor structure".
Minor errors
Page 4: please check. The emotional wellbeing sub-scale has 6 items (18 to 23) and the socialsupport sub-scale has 4 items (24-27). Naming of the sub-scales seems to have been swapped inerror.Page 8, typo, line 51 "on the on the"mments to the authors.
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.
YesAre 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 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:
AcceptableDeclaration of competing interests
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