Reviewer's report
Title:Pilot test and validation of the Peak Day method of prospective
determination of ovulation against a handheld urine hormone monitor
Version:1Date:20 November 2013
Reviewer: Penelope Howards
Reviewer's report:
OVERVIEW
This manuscript describes a pilot study to assess whether women can be taught
to monitor cervical fluid in order to identify ovulation for the purposes of field
research. Generalization of the results is limited by the fact that the study
population was a convenience sample of volunteers who may not represent the
target population of a field research study and by the small sample size,
particularly among the women who used the best quality algorithm, which
appears to be the best algorithm. These types of limitations are to be expected in
a pilot study, and the authors clearly indicate the study is a pilot study.
MINOR ESSENTIAL REVISIONS
1. One of the methods of recruitment was mailing letters. Who were the letters
mailed to?
DISCRETIONARY REVISIONS
Primary discretionary revisions
1. The rationale for the study would be strengthened if some specific examples
where the timing of exposure measurement needs to be precise (within a week)
were included in the introduction.
2. Another potential advantage to the Peak Day method might be to help time
clinic visits to key times in the menstrual cycle (whether for menstrual function
studies or pregnancy studies). This would be particularly useful for timing blood
draws.
3. Are there any data (from prior studies or this study) on the acceptability of the
Peak Day approach to women? How much did the study participants know about
the approach when they volunteered? Is this method likely to be sufficiently
acceptable to women for use in a population-based research study?
4. Could the content of the brochure be provided in an e-appendix or could a link
to the online brochure be provided?
5. Could you include a figure or chart that shows what women report (that the
experts reviewed)?
6. It is stated that the expert reviewers were simulating how the women would
have performed with clearer instructions (first paragraph in the section Fertility
Chart Expert Review), but there are two key differences. First, they are experts
and therefore presumably less likely to misinterpret the results. Second, they had
the advantage of knowing when menses occurred and therefore could exclude
premenstrual fluid from their assessment. The expert review is still a useful
assessment of how well the women learned the method, but they probably are
not representative of the women’s experiences.
7. If time and resources permitted, it would be nice to have naïve reviewers look
at the cervical fluid diaries (one day at a time so as not to show when menses
occurred in advance) and see if they picked the correct EDO. Naïve users would
more closely represent the experiences of the study participants, and this could
be used to increase the sample size for the best quality algorithm. Admittedly,
this is a pilot study so the sample size may be adequate to justify a larger study.
However, having naïve reviewers examine the diaries would be cheaper than
fielding a full study.
8. Did women ever not identify an EDO at all? If so, was it because they didn’t
ovulate or they couldn’t identify it? Could the method be used in studies to
identify annovulatory cycles?
9. Is there any information on what factors lead women to identify a day other
than the exact day the expert identified? For example, did the cycles where the
women and the experts differed by 3 days share any characteristics?
10. In the conclusion, it is probably worth reiterating that this is based on a pilot
study. Perhaps instead of stating the method is “well suited…” the sentence
could be rephrased to indicate the method is promising.
Minor discretionary revisions
1. The exposure questionnaire seems more prominent in the abstract than in the
paper. I would recommend either decreasing its prominence in the abstract or
discussing it further in the manuscript. If the exposure questionnaire was
removed from the abstract, then there would be room to add a sentence about
how the women’s choice of EDO compared to the expert’s choice.
2. The BioCycle Study is cited as a field study that uses a fertility monitor. The
cited paper is the background paper, but there is also a paper specifically
addressing the use of the fertility monitor that might be of interest (AJE 2009
169(1):105-12).
3. Did any of the women who identified their EDO to be just prior to menses
initially think their day of ovulation was earlier and then change their mind at the
end of the cycle? Could this be assessed by the fact that the women would have
filled out two exposure questionnaires?
4. In the first paragraph of the results, it is a little confusing whether the sample
sizes refer to cycles or women.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
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.