Reviewer ’s report  
 
Title:  Factors associated with deep infiltrating endometriosis versus ovarian endometrioma in 
China: A subgroup analysis from the FEELING study  
 
Version: 1 Date: 30 Apr 2018 
 
Reviewer:  Cristina Laguna B.  Pinto  
 
Reviewer’s report:  
 
The authors conducted a subgroup analysis to identify the factors associated to DIE versus 
OMA. These factors could help the clinical diagnosis, according to the authors.  
 
The study has a trial registration. The study protocol was approved by the institutional review 
boards in all institutions part icipating of the study, but the authors didn't inform if the women 
signed a written consent term prior to their inclusion.  
 
 
In my opinion, many points are not clear and need to be explained:  
 
1. Abstract is not good to allow a good understanding of the study . The conclusion should 
include the strong factors pointed out by the results.  
 
2. The authors didn't include the sample size calculation or the power test.  
 
3. They compared 156 women classified as OMA and 78 women as DIE, all of them with 
histological dia gnosis.  Why was the surgery indicated? Were the women using hormonal 
treatment to endometriosis? For how long? What kind of medication was used? Did they 
all had a US or MRI image with suspected endometriosis?  
 
4. Some variables are not clearly described in the section "methods" (eg in relation to 
feeding).  
 
5. Why was the normal BMI divided in two groups?  
 
6. Why was blood type B+AB grouped for analysis?  
 
7. If 21.3% of women in OMA group and 33.3% in DIE group were using hormonal 
treatment or were ex -users,  how did the authors characterize the cycles (regular or not) 
and ovulation disorders?  
 
8. How did the authors characterize ovulatory disorders? Why was the number of ovulatory 
disorders different from irregular cycles, once the data were obtained by interv iew?  
 
9. The number of some variables was to small to allow conclusions (irregular menstrual 
cycles, positive history of endometriosis)  
 
10. Some variables are statistically significant, but I am not sure whether the analysis has any 
sense (e.g.: have any s iblings, marital status) to be included as a potential factor 
associated to OMA or DIE and to help in the clinical diagnosis.  
 
11. In my opinion, although the authors have compared their results to others of the literature, 
they don't explain the results o btained or how they are correlated to the aim of the study: 
help the clinical diagnosis. They still need to include the weak nesses and strengths of the 
study.  
 
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Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in you r comments to the authors.  
 
Yes 
 
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 manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
Not relevant to this manuscript  
 
Quality of written English  
Please indicate the qual ity of language in the manuscript:  
 
Acceptable  
 
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