Title: Risk of uterine leiomyomata with menstrual and reproductive factors in premenopausal
women: Korea Nurses’ Health Study
Version: 0 Date: 26 Apr 2023
Reviewer:  Kyung-Hwa Choi
Reviewer's report:
The study titled "Risk of uterine leiomyomata with menstrual and reproductive factors in
premenopausal women: Korea Nurses’ Health Study" is valuable for women's health.
However, some points should be revised for publication.
Major issues
1. Please add the reference
“The second National Institutes of Health International Congress on advances in uterine
leiomyoma research: conference summary and future recommendations”
https://doi.org/10.1016/j.fertnstert.2006.02.116
The study reported that family history, alcohol use, exposure to insect repellent, and hereditary
leiomyomatosis renal cell carcinoma are risk factors for UL.
2. Please check it and add the family history as a risk factor in your analysis.
3. Please add the figure of the selection process of the study subjects. And please check the
numbers again.
4. You should analyze again Table 4.
In Table 2, you analyzed the association between menstrual characteristics and the risk of uterine
leiomyomata.
In Table 3, you analyzed the associations of reproductive history and oral contraceptive use with
the risk of uterine leiomyomata.
If you want to show something more, you should analyze the risk of menstrual characteristics,
reproductive history, and oral contraceptive use for uterine leiomyomata in the same model.
Therefore, first, you should figure out the correlation among the risk factors.
And then you should figure out the effect modifier. you can stratify with the effect modifier.
In my opinion, cycle length and cycle length ages 18-22 years may be highly correlated.
If those are highly correlated, you should not those factors in the same model due to
multicollinearity.
After those analyses, you should revise the whole of the manuscript.
Minor issues
'Background' section
1. "the cumulative incidence rate from 2002 to 2013 was 12.2% in Korean women"
Could be expressed in Incidence rate with %?
Is it prevalence?
2. "The prevalence of UL in Korean women was reported to be 9.0% in a self-administered
online survey [9] and 37.5% in a pelvic ultrasound study [10]"
Please add the calendar year and the age of the study subjects of the studies.
'Exposure assessment and covariates' section
1. "Participants were asked about their age at menarche (from < 8 to # 17 years), time to regular
menstrual cycles (from < 1 to # 5 years, and “always irregular”), and menstrual cycle patterns.
Questions on menstrual patterns included cycle length (from < 21 to 40–50 days, and “> 50 days
or too irregular to estimate”) and regularity in early adulthood (ages 18–22 years) and baseline. "
The categories in the sentences are very confusing because of the mismatch with Table 1.
2. "Possible risk factors such as obesity, hypertension, and alcohol drinking, have been shown
to be associated with UL [15, 22]. "
Please move the sentence to the Background section.
'Statistical analysis' section
1. "age at menarche (# 11, 12–13, 14–15, # 16 years); menstrual cycle lengths (< 26, 26–31, 32–
39, # 40 days or too irregular to estimate); parity (nulliparous, 1, 2, # 3 births); BMI (< 18.5,
18.5–22.9, 23.0–24.9, # 25 kg/m2); systolic blood pressure (< 105, 105–114, 115–124, 125–
134, # 135mmHg; blood pressure without medications), and a recent gynecological examination
(no, yes; Pap smear screening). "
Please move the categories to ‘Exposure assessment and covariates’ section.
'Discussion' section
You should discuss the recall bias of reproductive factors between UL case and the control group.
Table 1
Please add the information on person-years and f/u time in Table 1.
Pap spear screening ==>Pap smear screening
I don't understand why you differently use systolic blood pressure or diastolic blood pressure as
adjusting factors in Table 2, Table 3, and Table 4.
Further, you showed a distribution of diastolic blood pressure in Table 1, while mentioning only
systolic blood pressure in the Method section.