Reviewer's report
Title:The effect of past use of oral contraceptive on bone mineral density, bone
biochemical markers and muscle strength in healthy pre and post menopausal
women
Version: 1Date:8 November 2008
Reviewer: Adolfo Diez-Perez
Reviewer's report:
Comments for the authors
This paper reflects an interesting research with two main new facts that deserve
attention. First is the finding of an effect of oral contraceptives in physical
performance. Second, the study of a population from an Arabian country, where
the available information is more limited. However, some points need to be
solved before the paper would be considered suitable for publication.
1. The first point to be clarified is if in the premenopausal group of OC users
where women still taking OC pills. In methods this is confusing. The finding of
reduced remodeling for the two markers analyzed is consistent with active use in,
at least, a subgroup of subjects. This needs to be clarified because is well known
that the effects of estrogens on remodeling disappear quickly after stopping their
use. The authors in the discussion already mention this when they discuss about
BMD.
2. Along these lines, it looks like in premenopausal OC users there is a trend
towards higher BMD in all anatomical locations. Although the sample size is
small, if current users are mixed these might account for the trend and, in this
case, the lack of difference be only a power limitation for the low number of
current users.
3. In the physical performance test there is a potential confounder that is not
taken into account, and is the presence of osteoarthritis. This condition is highly
prevalent in this population and a protective effect of estrogens on their
development has been suggested. Therefore, some estimation of the degree of
OA could further strength the described association. BMI is associated with OA
degree and this could be a potential surrogate but, in any case, the authors
should, at least, discuss this point in the discussion and ideally provide some
data if available.
4. Another potential source of bias is the socio-economic and/or educational
level. It has been demonstrated that hormone users in the US were not
comparable in terms of physical exercise, diet and lifestyle with non-users. The
same might occur for OC users vs. non-users in the present study. Although
some of the variables are very similar (calcium intake, BMI,...) there are other
differences that, although non-significant, are at least remarkable as the number
of pregnancies in the premenopausal group. Again, additional information (and,
eventually, adjustment) needs to be provided or, at least, mentioned in the
discussion as potential limitation.
5. The manuscript needs a deep review of the writing by a native
English-speaking person because is plagued of mistakes. Moreover, some
technical words (Ward’s triangle instead of Word’s triangle) need also careful
review.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Not suitable for publication unless extensively edited
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests