Title: Obesity at age 20 and weight gain during adulthood increase risk of total and premature
all-cause mortality: Findings from women attending breast screening in Manchester
Version: 2 Date: 02 Oct 2022
Reviewer:  Emmanuel Biracyaza
Reviewer's report:
Dear authors,
I would liket to thank for producing this important study which was carried out in the area
which has been less researched in the most countries of the world. However, some clarifications
and changes are substantial before I recommend it for acceptation for publication. This study
is interesting for promoting the quality of life of the people with NCDs not only in LMICs but
also in HICs.
Abstract
The abstract needs to be improved by providing relevant ideas. For example; the background
lacks what interests the researchers to conduct the study and it does not indicate the study settings
and when the study was conducted (from baseline to endline).
Background
The study was conducted in a good topic that was less researched, however, it has some concerns
to be addressed. Although the study was conducted in Manchester or the UK, the readers need
to know how the situation is in the LMICs when compared to HICs like MUK.
Regarding your literature, you said that prevalence of obesity has increased rapidly in the US
and globally over the past several decades and this was also recently reported in the previous
studies. What do you think are the associated factors?
Example: Xie W, Lundberg DJ, Collins JM, et al. Association of Weight Loss Between
Early Adulthood and Midlife With All-Cause Mortality Risk in the US. JAMA Netw Open.
2020;3(8):e2013448. doi:10.1001/jamanetworkopen.2020.13448
The background needs to be improved by including more relevant literature. For instance; it
lacks the literature about the risk factors of mortality and how BMI and increased weight gain
during adulthood are the risk factors of  mortality among T2DM patients.
Methods
You said “The PROCAS study has been reported in detail elsewhere”. Please, provide the
description in this part so that the readers understand the PROCAS.
Some parts of the methods are missing such as study design, study settings and its description,
data collections, sampling methods and sample size, study variables (outcome variable,
explanatory variable, moderate variables, mediator variables etc.), and ethics statements. Indeed,
some variables were not assessed such as behavioral variables (e.g. smoking etc.) Why not?
Although you did not seek the ethical approval, the ethics statement is important in your methods
section.
In the analysis, cox proportional hazards regression models should be used to estimate the
association between weight change patterns and all-cause mortality in the total sample, adjusting
for the covariates that could be described in the methods sections.
Also, the effect modifications or effect size could be assessed in the covariate and multiple
regression analysis. why? Indeed, how long did the follow-up take? how the sample
characteristics changed by weight change patterns from age 20 years to that time before the
baseline? Then, how may they maintain their weight, how many gained and lost their weight in
that period between the baseline and the endline?
Some statistical analysis such as population-attributable fraction (PAF) can be important to
measure early deaths and adjusted cumulative hazard curves of all-cause mortality for weight
change patterns for all individuals? Why not in this study?
Results
The results can be improved based on the comments provided in the methods sections.
Meanwhile, the descriptive analysis of the respondents needs to be well provided in the current
study.
Discussions
Please, the subheading strengths and limitations may be combined and then remain with the
subheading “Strengths, limitations and public health implications”.
Tables and figures
Please, you are presenting the tables and figures you have to indicate the title of each column
(for example; you provided the values in table 1 and table 2) but we cannot know if they are %,
frequency or any further statistical parameter. Please, you have to increase clarity and visibility
of your tables as well to facilitate the readers.
Conclusion
Please, improve the conclusion including the prevalence and the risk factors based on the results
indicated in the models 1 and models 2. Then, remember that the recommendations to the policy
makers and to the further researchers are also substantial.
General comments
Please, write well the word “years” instead of “y”
When you write the word at the first time, you avoid using abbreviations but full words and
abbreviations in brackets. For example, the NHS , UK, BMI etc.
I think that it is better to say type 2 diabetes mellitus (T2DM) instead of type 2 diabetes (T2D).
Check well in the manuscript.
It is important to provide your declaration sections after the conclusion before you start the
references sections. I can also advise you to check well the structures of the BMC journals
about the sections of the declarations sections. The declaration section you provided needs to
be clarified and/or improved as well.
References
Some references are not complete.
example; You have to provide the link of the references that follow 1, 5, 9 and 21. For the
remaining, it is also important to provide their DOI to facilitate the reviewers to access them.