Risk of Obstetric Anal Sphincter Injury by Delivering Provider^†

Round 1

Reviewer 1 Report

1. What is the main question addressed by the research?

This paper has the aim to asses if the primary delivering provider is associated to obstetric anal sphincter injury.
2. Do you consider the topic original or relevant in the field? Does it
address a specific gap in the field?
The topic is relevant because it’s a retrospective cohort study which collected birth data from 228,668 de- 55 liveries from 19 hospitals within 12 institutions across the United States from 2002 to 2008.
3. What does it add to the subject area compared with other published
material?
This paper is special because it presents a comparation between the type of delivering provider as a risk factor for OASI.
4. What specific improvements should the authors consider regarding the
methodology? What further controls should be considered?
No specific improvement needed.
5. Are the conclusions consistent with the evidence and arguments
presented and do they address the main question posed?
Conclusions are consistent with the main purpose of this paper,
6. Are the references appropriate?
The references are appropriate
7. Please include any additional comments on the tables and figures.
Tables are well made

Author Response

We would like to thank the reviewer for their evaluation of our work and thoughtful feedback. 

Reviewer 2 Report

Overall, a very well written and interesting study. The introduction provides sufficient background and context for the study and includes relevant supporting literature. There is a clear patient outcome focus, which adds value to your work. The methods are clearly described and your data analysis approach is rigorous for this type of study. This section may benefit from some sub-headings.  

The results are presented well - the tables are clear and include relevant outputs aligned with the aim of the study. Including the p values may be useful, but I note they are mentioned in the text. 

The discussion is high level and demonstrates impact for future decisions. A noted in your limitations, some further research around the training level of physicians, and experiences of physicians and midwives would be beneficial to explore factors impacting OASI further. The concluding statements link nicely to your overarching aim and demonstrate value for real world practice and patient-centered outcomes. 

Two minor suggestions for change included below. 

Line 33 - the opening sentence has some inconsistency with previous terminology in abstract. Is it "obstetric" or "obstetrical"? I suggest keeping these terms consistent throughout. 

It would be beneficial to include some updated references, most are from >6 years ago. 

Author Response

We would like to thank the reviewer for their complete evaluation and recommendations. The following changes have been made:

1. Line 33: Obstetrical was changed to obstetric. In addition, this was changed in lines 30 and 119 to match the rest of the text.
2. This is a great point regarding the references. A search was conducted using pubmed and there were no more relevant and recent studies than 2019, which we included here. 

Reviewer 3 Report

The article is interesting because it correlates the occurrence of OASIs with the type of delivery care that is provided to the patient. It is clear, however, as already pointed out by the authors, that medical delivery care is directly correlated with clinical characteristics of patients who require more medicalization and interventions during delivery. In particular, all the factors that make labor non-physiological and all those risk factors of pregnancy make possible complications such as OASIs more likely. This factor, related to the extreme variability of the general population, does not allow for a univocal conclusion on the incidence of medical or obstetric care in the occurrence of delivery complications.

Author Response

We would like to thank the reviewer for their complete evaluation of our work. Yes, while the characteristics of the populations with and without OASIs are different, when we controlled for those characteristics in propensity matching, physicians were still more likely to have OASIs compared to midwives. Lines 132- 136: "Additionally, propensity score matching was conducted to ensure the strength of the regression model. A propensity score match was used to balance all potential confounders. We found 1,054 matches per cohort with OASIs rates of 6.6% and 1.8% for physicians and midwives, respectively. Physician was associated with 3.8 higher odds of OASIs relative to midwife (95% CI2.0- 7.; p=0.0002)."

No text was changed.