Reviewer's report
Title:Maternal hair selenium levels and recurrent pregnancy loss.
Version: 1Date:31 October 2012
Reviewer: Hiten Mistry
Reviewer's report:
This paper explores maternal hair selenium concentrations in a group of
non-pregnant women who have suffered from recurrent pregnancy loss and
compares them to matched healthy controls. The findings of the study show that
there were no differences in the selenium concentrations between the groups,
but there were differences in the household incomes and food intakes.
- Major Compulsory Revisions:
1. It would be good f the authors could included in the introduction the reason
why hair samples were used to measure long term selenium concentrations as
compared to toenails, which have been shown to be a more reliable
measurements of this (Rayman et al, 2000). A couple of additional sentences
would be good here.
2. Also, many of the studies that have been referenced in the introduction in
relation to recurrent miscarriage relates to maternal serum or red-call selenium
concentrations and not hair. Therefore, it is important to further justify the choice
of using hair.
3. Please add in a hypothesis at the end of the introduction.
4. In the methods section, there are a few important sections that need to be
included; these are as follows:
- Were the hair samples blinded as to which group they were from?
- Were each of the samples run in duplicate/triplicate and if so please state this
and include the CoVs for both the inter- and intra assays.
- There needs to be a section on the statistical analysis that was performed in the
study. Details of whether the data was tested for normality, and then what
subsequent tests were carried out. Details of how the data is represented (i.e.
means plus/minus SD or median [IQR] and the ‘p’ value used for significance
also needs to be included.
-A power calculation for the number of samples used in each group should also
be included.
5. Table 3 reports selenium levels in the hair as mean (SD), however in the text a
Mann-Whitney U test was carried out indicating that the data was in fact
non-parametric. If this is the case, then the table should actually show the
median [IQR] as this is the most appropriate way to present non-parametric data.
6. In the discussion there are some conflicting statements, as the authors first
state that ‘...possibly stating higher selenium in South African soils and foods’
and then in the next paragraph suggesting ‘ selenium deficiency in soil and
therefore agricultural products has been demonstrated in South Africa.’ This
should be addressed in any further revisions.
- Discretionary Revisions:
1. There have been several good reviews of selenium in reproductive health and
pregnancy in recent years and it would be good if these were referenced to allow
non-specialist readers with an interest in selenium to know about these.
2. Was there any reasonable explanation for the 3 RPL patients that had
selenium concentrations below the detectable limits?
3. It would be good in the discussion to try and provide an explanation as to why
Al-Kunani et al’s study showed different results to the current study.
4. As mentioned above, it would be good if the authors could include a section on
the limitations of the study and a further justification as to why they used hair
instead of blood or toenails to complete their analysis on in the discussion.
5. In addition, to this, it may actually be the short term selenium concentrations
(i.e. circulating serum or red-cell selenium concentrations) that are involved in
RPL as has been shown by Barrington et al’s and other studies. Therefore, it
may be worth making this point in the discussion.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
- Have you in the past five years received reimbursements, fees, funding, or
salary from an organisation that may in any way gain or lose financially from the
publication of this paper, either now or in the future? NO
- Do you hold any stocks or shares in an organisation that may in any way gain
or lose financially from the publication of this paper, either now or in the future?
NO
- Do you hold or are you currently applying for any patents relating to the content
of the manuscript? Have you received reimbursements, fees, funding, or salary
from an organization that holds or has applied for patents relating to the content
of the manuscript? NO
- Do you have any other financial competing interests? NO
- Do you have any non-financial competing interests in relation to this paper? NO
I declare that I have no competing interests.