Evaluation of weight retention four weeks after delivery as a risk factor for gestational diabetes mellitus in a subsequent pregnancy

Satoshi Shinohara; Atsuhito Amemiya; Motoi Takizawa

doi:10.1371/journal.pone.0231018

Peer Review History

Original SubmissionNovember 11, 2019
2 Mar 2020 Decision Letter - Zhong-Cheng Luo, Editor PONE-D-19-31440 Evaluation of weight retention four weeks after delivery as a risk factor for gestational diabetes mellitus in a subsequent pregnancy PLOS ONE Dear Dr Shinohara, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. We would appreciate receiving your revised manuscript by Apr 16 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. 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Please add a cloumn for the accurate P value to the precision of 3 decimal points for the adjusted OR in Table 2. 3. Line 184, why stated "(data not shown)" when you acturally presented the data? Journal requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at http://www.journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and http://www.journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. 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You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The question about weight gain and retention and its impact on pregnancy outcomes is an important issue. There a number of points that need clarification. 1. Was the pre-pregnancy weight for calculation of the BMI at the first visit self-reported? 2. How was the screening for GDM performed? Was it a 1-step or was there pre-screening with random BSL or GCT as both of these have been shown to miss up to 20% of cases of GDM? Understanding this is important for the non-Japanese reader. You have made comment in your discussion that you were measuring weight retention at 4 weeks postpartum that may not accurately reflect the final post pregnancy return to the non-pregnant state. It was not clear if you have made adjustment for the gestational length of the pregnancy as this may have a significant impact on the total weight gain and therefore the peak level from which the woman has to lose weight in returning to the non-pregnancy state. Reviewer #2: In this paper, the authors analyzed 4 week postpartum weight retention (PPWR) using BMI in the 4th week after delivery in 566 nondiabetic, Japanese women with the risk for GDM in a subsequent pregnancy. A Stable PPWR (4 wk BMI – 1st pregnancy prepregnancy BMI) < 1 BMI unit means that the individual lost almost all of their pregnancy weight gain by 4 weeks, correct? The definition of non-stable PPWR (gain of > 1 BMI unit) is only defined in the Abstract and should again be defined in the Methods and repeated in the results. They found no difference in the risk for GDM according to their separation of groups according to BMI change at this 4 week follow-up visit, at which only about 1/3 of women had come back to < 1BMI difference from their prepregnancy BMI. They did find that obesity and interpregnancy weight gain, as expected, were risk factors for GDM. Could the authors analyze the PPWR among those who were obese compared to those not obese? Probably not, as the proportion who were obese was very low (71/566). The authors could mention in their Discussion, that given the current results, attention should be paid to women with the traditional risk factors of obesity, weight gain during pregnancy, prior history of GDM and family history of GDM rather than PPWR – especially at 4 weeks. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. 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Revision 1
11 Mar 2020 Author Response March 5, 2020 Zhong-Cheng Luo Academic Editor PLOS ONE Dear Editor: I, along with my co-authors, would like to re-submit the attached manuscript, titled “Evaluation of weight retention four weeks after delivery as a risk factor for gestational diabetes mellitus in a subsequent pregnancy” as an original research article (manuscript ID: PONE-D-19-31440). We appreciate your valuable comments, which have been very useful to us in improving the quality of our manuscript. All changes are shown in red in the revised manuscript. The entire manuscript has been also rechecked, and the necessary changes have been made in accordance with your suggestions. Our point-by-point responses to all of your comments have been prepared and provided below. We believe that the changes made based on your comments have significantly improved our manuscript, and we hope that you will find it suitable for publication in PLOS ONE. Sincerely, Dr. Satoshi Shinohara Department of Obstetrics and Gynecology National Hospital Organization Kofu National Hospital 11-35 Tenjin, Kofu, Yamanashi 400-8533, Japan Tel: +81-55-253-6131 Fax: +81-55-251-5597 Email: shinohara617@gmail.com RESPONSES TO THE EDITOR’S COMMENTS Comment 1 Please add an ad hoc power calculaition for detecting a 2-times risk elevatation in GDM comparing postpartum BMI change >=1 (unstable) vs <1 (stable) in the Discussion. You observed almost 2 times risk elevation (adjusted OR=1.93), although it was not statistically significant. This may be due to the lack of or insufficient study power to detect a risk difference. If this is true, data interpretation should be adjusted for accordingly. Response 1 Thank you for your comment. We reviewed the sample size again according to your comments. When performing logistic analysis like this study, it seems that the sample size is often determined based on events per variable (EPV) rather than per ad hoc power calculation (A-C). Calculating the required sample size based on the previous report (10 EPV is a widely adopted minimal guideline criterion for performing logistic regression analysis), we needed at least 60 GDM women during the second pregnancy in this study. Therefore, since this study only included 42 GDM women during the second pregnancy, there is a possibility of the lack of or insufficient study power to detect a risk difference as pointed out. Therefore, we added in the limitation section; “According to the sample size calculation method widely used when performing logistic analysis, “Ten Events Per Variable” is a widely adopted minimal guideline criterion for performing logistic regression analysis. Based on this method, we needed at least 60 GDM women during the second pregnancy in this study. Since this study only included 42 GDM women during the second pregnancy, there is a possibility of the lack of or insufficient study power to detect a risk difference.” A) Peduzzi P, Concato J, Kemper E, Holford TR, Feinstein AR. A simulation study of the number of events per variable in logistic regression analysis. J Clin Epidemiol. 1996;49: 1373-1379. B) Moons KG, de Groot JA, Bouwmeester W, Vergouwe Y, Mallett S, Altman DG, et al. Critical appraisal and data extraction for systematic reviews of prediction modelling studies: the CHARMS checklist. PLoS Med. 2014;11: e1001744. C) Moons KG, Altman DG, Reitsma JB, Ioannidis JP, Macaskill P, Steyerberg EW, et al. Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD): explanation and elaboration. Ann Intern Med. 2015;162: W1-W73. Comment 2 Please add a cloumn for the accurate P value to the precision of 3 decimal points for the adjusted OR in Table 2. Response 2 Thank you for your comment. Following your comment, we revised Table 2. Comment 3 Line 184, why stated "(data not shown)" when you acturally presented the data? Response 3 Thank you for your comment. According to your comment, we added Table 3, and “Finally, a multiple logistic regression model, into which we entered PPWR as a continuous variable, was performed. After controlling for each variable, a history of previous GDM, and obesity were significantly associated with GDM in the second pregnancy (history of previous GDM: adjusted OR, 7.70; 95% CI, 3.08–19.2; obesity: adjusted OR, 4.13; 95% CI, 1.91–8.95) in the multivariable logistic regression analysis. PPWR was not significantly associated with GDM in the second pregnancy (adjusted OR, 1.19; 95% CI, 0.94–1.50) (Table 3).” in the result. RESPONSES TO THE REVIEWER 1’S COMMENTS Comment 1 Was the pre-pregnancy weight for calculation of the BMI at the first visit self-reported? Response 1 Thank you for your comment. The pre-pregnancy weight for calculation of the BMI at the first visit was self-reported. We added, “The pre-pregnancy weight for calculation of the BMI at the first visit was self-reported.” in the data collection. Comment 2 How was the screening for GDM performed? Was it a 1-step or was there pre-screening with random BSL or GCT as both of these have been shown to miss up to 20% of cases of GDM? Understanding this is important for the non-Japanese reader. Response 2 Thank you for your comment. We added “In Japan, an initial screening test followed by the diagnostic oral glucose tolerance test (OGTT) in screen-positive women, known as the two- step approach, is used for GDM diagnosis [16]. Moreover, the Japan Society of Obstetrics and Gynaecology has recommended the 50 g glucose challenge test (GCT) as a screening method for GDM [16]. Women with abnormal GCT results (serum glucose levels ≥140 mg/dL) subsequently undergo a 75-g OGTT for a definitive diagnosis.” in the data collection. Comment 3 You have made comment in your discussion that you were measuring weight retention at 4 weeks postpartum that may not accurately reflect the final post pregnancy return to the non- pregnant state. It was not clear if you have made adjustment for the gestational length of the pregnancy as this may have a significant impact on the total weight gain and therefore the peak level from which the woman has to lose weight in returning to the non-pregnancy state. Response 3 Thank you for your comment. Following your comment, we added an analysis of the gestational length of the first pregnancy in Table1. RESPONSES TO THE REVIEWER 2’S COMMENTS Comment 1 A Stable PPWR (4 wk BMI – 1st pregnancy prepregnancy BMI) < 1 BMI unit means that the individual lost almost all of their pregnancy weight gain by 4 weeks, correct? The definition of non-stable PPWR (gain of > 1 BMI unit) is only defined in the Abstract and should again be defined in the Methods and repeated in the results. Response 1 Thank you for your comment. According to your comment, we changed from “We classified women according to their postpartum check-up PPWR and defined a stable PPWR as ≤1 BMI unit, per previous relevant publications” to “We classified women according to their postpartum check-up PPWR and defined a stable PPWR as ≤1 BMI unit and non-stable PPWR >1 BMI unit, per previous relevant publications” in the Methods. Moreover, we changed from “The characteristics of women with and without were similar except for greater first and second pregnancy, pre-pregnancy BMIs and lower first pregnancy, postpartum checkup BMIs in the stable PPWR group (Table 1).” to “The characteristics of women with a stable (≤1 BMI unit) and a non-stable PPWR (>1 BMI unit) were similar except for greater first and second pregnancy, pre-pregnancy BMIs and lower first pregnancy, postpartum checkup BMIs in the stable PPWR group (Table 1).” Comment 2 They found no difference in the risk for GDM according to their separation of groups according to BMI change at this 4 week follow-up visit, at which only about 1/3 of women had come back to < 1BMI difference from their prepregnancy BMI. They did find that obesity and interpregnancy weight gain, as expected, were risk factors for GDM. Could the authors analyze the PPWR among those who were obese compared to those not obese? Probably not, as the proportion who were obese was very low (71/566). The authors could mention in their Discussion, that given the current results, attention should be paid to women with the traditional risk factors of obesity, weight gain during pregnancy, prior history of GDM and family history of GDM rather than PPWR – especially at 4 weeks Response 2 Thank you for your comment. According to your comment, we added “According to the current study results, attention should be paid to women with the traditional risk factors of obesity, the interpregnancy BMI change, prior history of GDM and family history of GDM rather than PPWR – especially at four weeks after delivery.” and “In this study, there was no significant difference in PPWR between obese and non-obese women (1.20±2.29 vs. 1.53±1.28 BMI unit, p=0.51)” in the discussion. Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0231018.r002
16 Mar 2020 Decision Letter - Zhong-Cheng Luo, Editor Evaluation of weight retention four weeks after delivery as a risk factor for gestational diabetes mellitus in a subsequent pregnancy PONE-D-19-31440R1 Dear Dr. Shinohara, We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements. Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication. Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. With kind regards, Zhong-Cheng Luo Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0231018.r003

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