Title: Clinical factors associated with quality of life among women with endometriosis: a cross-
sectional study
Version: 1 Date: 06 Jul 2023
Reviewer:  Anneke M. F. Schreurs
Reviewer's report:
This manuscript is a well written report on the determinants of QoL in women with
endometriosis. Even though this is an important research that is entitled to publication in the
future, I have some concerns to address first. Hopefully this will enhance the quality of the
research and improve the usage and interpretation of the data for future research.
A few points I would like to comment:
Abstract
- conclusion: i do not understand how you conclude that patient-centeredness should be
improved when correlations are mostly found between mental health issues / opioid use and QoL.
Introduction
- please describe what is known already about the relation between symptom severity and QoL
(short explanation of what is found in reference 10, 12 and 13).  This information is relevant to
understand/interpret the rest of your findings.
Methods
- please add the reference of the original development of the EHP-30 (Jones et al 2001).
- please bear in mind that, officially, the total EHP-30 score does not exists and has not been
validated (at least in the original development). The EHP-30 should be presented for all 5
domains. The domains cannot be treated as equals (also they have a different amount of questions
per domain) and should not be pooled. Please explain the choice to use it.
Seriously consider presenting the results per EHP-30 domain as also presented by Apers et al.
- the cut of of p-value 0.05 is very strict for the univariate regression analysis. Often the cut
off is set at 0.2 to be sure not to miss correlations that come forward during the multivariate
regression analysis. Why is this chosen?
Results
- I do not understand why the answer 'do not know' on the question of endometriosis severity
is pooled with 'minimal' and 'mild'. Please remove the 'do not know's from the 'minimal/mild'
group and retest the relation.
- in previous research 'the  number of visits to the GP before referral' was difficult to interpret
as some women set this number at '100'. This really influences the average number. The
characteristic was therefore dichotomised in previous research. What was the reaction here? It
is hard to interpret from a mean +/- SD. If it is even a little similar to previous research, this
result should be presented as a median/IQR.  please consider dichotomising this characteristic.
Please be more critical about presenting results as means/medians.
- did you check for the relation between 'having had endometriosis symptoms in the past
year' (one of the questions in the ECQ) and using opioids in relation to QoL? Is it the fact that
women are in pain that they score the QoL worse? Or is there another effect from the fact that
they have to use opioids? The first seems the most logic, and could be easily evaluated with the
data you have. Also the relation with the EHP-30 domain 'pain'  could be evaluated separatly.
Discussion
- please explain the relation with mental health issues in more detail than the single line it gets
now.
- you state that the correlation with age is only very limited. But please understand that this
correlation is for one years difference. So if there is a difference of 10 years at the age of first
symptoms this could potentially lead to a difference of 6.4 on the QoL score. Please rephrase this
in the discussion (you do not have to add the 6.4 point difference, because you did not evaluate
it for 10 years difference)
- I do not understand why you state that women who use opioid have more mental health issues.
What is this based on? Please remove or add a reference.
- please substantiate your statements in the discussion. Recall bias for the past four weeks? There
is a lot of data on recall in endometriosis complaints, is it correct what you state? Only very
limited studies include only women with self-reported endometriosis (none of the ENDOCARE
studies) Is your response rate similar to others? You only added 5 new references to your
discussion. Please use this discussion to really compare your data with other current knowledge.
Conclusion
- how do you want health care providers to use your presented results? Please describe how this
can be relevant. I do not understand the relation between opioid use and mental health issues
and improving patient-centeredness.
I am looking forward to the response.