Reviewer ’s report  
 
Title: THE REPRODUCIBILITY OF SELF -REPORTED AGE AT MENARCHE. THE  
TROMSØ STUDY  
 
Version: 0 Date: 14 Apr 2017  
 
Reviewer: Gillian  Einstein  
 
Reviewer's report:  
 
This is a useful study that aims to replicate the previously assessed reproducibility and validity of 
self-reported age at menarche. The results support the reproducibility of self -reported age at 
menarche within a particular population. The authors utilize a sample from two large population 
studies taken seven years apart, including only women who participated in both studies. While 
previous studies show reproducibility in self -reported age at menarch e, this study improves upon 
the limitations of previous studies by using a larger sample size, a comprehensive age 
stratification, and a greater time between the two studies. Furthermore, the use of a Bland -
Altman plot along with correlation coefficients h as allowed for a more sophisticated analysis 
including the limits of agreement. However, an improved argument for the implications of 
reproducing self -reported age of menarche is necessary, as well as a deeper discussion of health 
conditions this informati on might impact, as neither of these are fully explicated in the current 
text. It would add depth to this study if the authors elaborated on relevant conditions and the 
overall problem of disbelief in women's self -reports. The manuscript would benefit from  a more 
defined argument for its importance in the literature and methodological implications. It would 
be very useful to know if in addition to self -report being reproducible if it can also be confirmed 
that reported age is actually in agreement with the actual age at menarche as evidenced through 
medical records. Only then can the the claim that self -reported age at menarche is actually the 
"true" age at menarche.  
 
 
Below, by section, are further suggestions for strengthening this manuscript and its concl usions.  
 
 
 
Abstract:  
Grammatical  
 
 
1. Line 26: Remove "e.g." and just include the three limitations discussed in the 
background, as two are already listed  
 
 
 
 
 
Background Section:  
 
1. Line 51: In what way have age at menarche and morbidity/mortality later in lif e been 
linked? I assume earlier age at menarche would be linked to earlier mortality, but you 
need to clarify the directions of this statement  
 
 
2. Line 53: What public health implications? A couple examples would be useful here.  
 
 
3. Line 59 -60: Mentions inve stigating two trends in menarche, however, the evidence for 
these trends has not been developed in the previous two paragraphs —mortality is only 
briefly mentioned, and adolescent behavior is not mentioned at all.  
 
 
 
grammatical  
 
4. Line 77: Unclear what "age g roups included (adolescents, older women)" refers to in 
terms of a limitation. Are you saying that only adolescents' and older women's recall of 
menarche has been previously researched? A rewording of this phrase might clarify.  
 
 
5. Line 50: Grammatical error, should read "It is a significant event, which has received"  
 
 
6. Line 52: Same error as above, have should be changed to have to reflect the singular 
"trend"  
 
 
7. Line 76: "relatively low to number" -"to" appears to be a typo, s entence would read better 
if removed  
 
 
 
Methods Section:  
 
8. More detail on the overall Tromsø study would be useful —origins, objectives, etc. What 
was it about?  
 
 
9. A copy of the English translated questionnaire might be good to add as an appendix.  
 
 
10. Line 1 03-104: (wives and children) to previously identified high risk men were invited to 
participate [21]. Please clarify if the whole study includes men. Would change 'wives' to 
women.  
 
 
11. Line 103 -104: Unsure what this "high -risk men" detail means, or why the se women in 
particular were invited to participate. Did the Tromsø study have a motive related to this 
risk? If so, it would be useful to include a sentence explaining the motives for the 
creation of the surveys.  
 
 
12. Line 132 -134: Unsure if this characteri stic is a hypothesis of your study, or whether it is 
just provided as an example of the types of observations that can be made with a Bland -
Altman plot. Furthermore, were there any hypothesized results or was this research 
purely exploratory?  
 
 
13. Is the ac tual age of menarche in these women known? If it's not known, how can one 
determine accuracy? They might not differ in their reported age from Tromsø 3 to 
Tromsø 4, however that does not necessarily mean that the reported age is actually their 
age at menar che. They may just be reliably reporting an incorrect age. A discussion of 
this potential confound should be included, and would be useful in future studies to 
compare this reproducibility with the actual age at menarche reported by their childhood 
doctor in medical records.  
 
 
 
Results Section:  
 
14. All the results should report effect sizes.  
 
 
15. Line 151: The difference is only between the mean of each study period not between 
actual age of menarche and stated age. As it stands, this just shows that the age  of 
menarche has not changed significantly between both time points.  
 
 
16. Line 154 -155: Did you hypothesize that the difference would attenuate with increasing 
age? If so, this should be made clear in previous sections.  
 
 
17. Line 173: Is -1.52 - 1.54 years o ff for the limits of agreement a small or large amount in 
research involving age at menarche? To rephrase, how confounding would it be for a 
participant to report an incorrect age within these limits? In order to fully interpret the 
limits of agreement, we  need more information on how a disagreement of this magnitude 
would impact the validity of menarcheal research.  
18. Line 175 -177: Was this hypothesized? In both this statement, and the above result, it 
reads as if this was a hypothesis. If so, your hypoth eses need to be stated, and if not, you 
need to clarify that this research was exploratory.  
 
 
19. The reliability of the finding that the 65 -74 year old group had the highest concordance 
with their previous report of age of menarche could be questioned beca use this group had 
only 65 participants. As mentioned in the Discussion (which should be reported in the 
Results) they comprised only 1% of the total sample.  
 
 
 
Discussion Section:  
 
20. Line 227 -228: It should be noted that the highest level of agreement (r =  0.91) in the 65 -
74 year -old group may be partially influenced by the fact that this group only made up 
1% of your total population. If there was a greater number of women in this age group, 
there may be more chances for disagreement and therefore a lower 
correlation/concordance in this group  
 
 
21. You should discuss implications of these findings. In your introduction, you allude to the 
necessity of accurate age at menarche for two major associations in adolescent behavior 
and mortality later in life, so thi s would be a great place to develop those ideas further.  
 
 
22. The earlier mentioned future direction of comparing this reproducibility with the actual 
age at menarche reported in medical records should be discussed here, along with any 
other future directio ns for this research.  
 
 
23. The Strengths and Weaknesses section should be expanded to include some of the 
mentioned shortcomings of the study.  
 
 
 
grammatical  
 
24. Line 217: "grown up" should be changed to adult  
 
 
25. Line 218: Typo in "and the relatively long time pasted since menarche"  
 
 
26. Line 219: "adjust" should be "adjusted" to reflect past tense  
 
27. Line 217 -220: This sentence has a whole would benefit from being rephrased to better 
reflect the core concept it displays  
 
 
 
 
Conclusion Section:  
- Major Revisions:  
 
1. Add the findings on limits of agreement, as it seems important that not only is there high 
levels of concordance, but even when there is not perfect concordance, women will 
typically be accurate within 1.5 years of their previous repo rt. 
 
 
 
grammatical  
 
2. Line 249: Maybe use "older women" and "younger women" —calling women aged 65 -73 
"old women" could be offensive.  
 
 
 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manuscript o r would you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
 
Quality of written Englis h 
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being pu blished  
 
 
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. 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  
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose  
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of the  
manuscript?  
 
4. 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?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write  'I declare that I have no competing interests' 
below.  If your reply is yes to any, please give details below.  
 
We declare that we have no competing interests' below. If your reply is yes to any, please give 
details below.  
 
Rebekah B. Reuben  
Gillian Einstein  
 
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