Title: Different clinical parameters inform Epicardial Fat Thickness in pre- and post-menopausal
Women with Obstructive Sleep Apnea
Version: 3 Date: 10 Apr 2021
Reviewer's report:
The present cross-sectional study investigates the effect of menopausal status on epicardial fat
thickness (EFT), a marker related to coronary artery disease, in a group of female patients with
obstructive sleep apnea (OSA). The authors have found that EFT was higher in the post/late
peri-menopausal group (Group 2) compared with the pre/early peri-menopausal group (Group
1) of patients. In addition, several correlations between EFT and anthropometrics/sleep indices
were noted in both groups, while independent predictos of EFT were AHI in Group 1 and
both AHI and BMI in Group 2. Although this study presents novel findings regarding the
relationships between OSA, EFT and menopausal status, there are some issues that need to be
further addressed.
Comments:
1. First, did the authors estimate an effective sample size in the present study using power
analysis? The number of included patients is relatively small and whether the study is
underpowered or not for the main outcome should be clarified.
2. Second, although there is novelty in the present article, I have missed the clinical relevance
of the study results. This should be more clearly supported before the study hypothesis in order
to support at first the design of the present study and thereafter to be more clearly highlighted
in the discussion section.
3. Third, the two groups are not matched and differ significantly in terms of BMI. As previously
acknowledged that EFT and BMI are strongly associated, did this relationship might have
influenced the study results, and specifically the differences of EFT levels between the two
groups?
4. Moreover, the authors mentioned in the study background that EFT is thicker in OSA patients
with metabolic syndrome. How is this relevant to present study? Did the authors accounted for
the role of metabolic syndrome using the criteria for defining metabolic syndrome? The latter
should be further examined as it could contribute to worsened levels of EFT in OSA patients.
5. Additionally, did the included participants receive a recent OSA diagnosis or were there
also included patients with a pre-existing OSA? For what reason did the patients referred for
assessment of OSA? Female patients with OSA often report fewer symptoms related to OSA
than male patients, and demonstrate other features which increase the likelihood of having OSA.
6. Furthermore, there is a lack of information regarding the history of sleep habits of the
examined patients. For instance, there is no report regarding the presence or not of daytime
sleepiness and snoring as well as the potential coexistence of insomnia with OSA. These
symptoms are strongly associated with an elevated risk of CVD and may have also additive
effects on EFT in OSA population.
7. Could the authors also examine the independent predictors of EFT in the whole sample of
patients and not only separately in the two groups?
8. I would avoid reporting the lack of measurements of vitamin D and thyroid hormones in the
limitation section, as this is a different study design. I would rather suggest to replace it with the
perspective of investigating the role of OSA treatment (PAP therapy, alternative treatments etc)
on EFT in relationship with the menopausal status.
9. Please avoid repetitions in the conclusion as you have previously summarized the findings
on the first paragraph of the discussion.
10. Moreover, I would suggest improving the presentation of the Discussion as there points
which should be more analyzed and not just simply stated. For instance, "This is in accordance
with previous findings where AHI is considered as a potential marker for postmenopausal
women without hormonal replacement therapy [20]. High BMI was a main independent
risk factor for postmenopausal women", or "Additionally, Li et al. reported a BMI-snoring
association, and lower BMI was a protective factor for premenopausal women...However, the
results are controversial".
11. Finally, please rephrase this sentence: "All subjects were enrolled before receiving written
informed consent".