Factors Influencing Quality of Life after Massive Weight Loss—What Makes the Difference?

Round 1

Reviewer 1 Report

An interesting article is presented, however, a series of observations and suggestions are made to improve it. Congratulations.

The authors can further emphasize the fact that the modality of weight reduction (conservative or surgical) does not matter, since only two lines appear in the conclusion. You may think that bariatric surgery is the solution for obesity, but this study proves otherwise. Not all people with obesity can aspire to surgery of this type and not all want to have it performed.

Abstract: The explicit objective must appear. In the results section, since it is a quantitative study, the statistics of the comparison (conservative vs. surgical) and of the correlations (magnitude, direction and probability) among BMI, body image and quality of life or at least the probability level values.

 

Introduction: In this section it is addressed that the evaluation of the quality-adjusted life years (QALY) or disability-adjusted life years (DALY) represent essential tools for efficiency calculation and cost-benefit optimization in today's health care system. But it is not observed in the results, nor in discussion, it is suggested to be reconsidered to indicate the role that the above plays in the study that is presented.

Results: In statistical analyzes, it is not clear if the authors calculated the regression coefficients or only calculated the determination coefficients (R2), since other indicators of this type of statistical analysis are observed, such as the value of Beta, of the ANOVA, of the probability of error, etc. In this regard, it should be noted that these determination coefficients in all cases are very low (.001 to .110). The authors must provide explanations in this regard (for example, it may be due to mediating variables), which requires greater study.

References: From 39 references only 10% are 5 years to date, it is suggested to update some of them.

 

Author Response

An interesting article is presented, however, a series of observations and suggestions are made to improve it. Congratulations.

We thank the reviewer for his work and for helping us improving our manuscript.

The authors can further emphasize the fact that the modality of weight reduction (conservative or surgical) does not matter, since only two lines appear in the conclusion. You may think that bariatric surgery is the solution for obesity, but this study proves otherwise. Not all people with obesity can aspire to surgery of this type and not all want to have it performed.

Thank you for highlighting this. We have re-written the conclusion focusing more extensively on this finding.

Abstract: The explicit objective must appear. In the results section, since it is a quantitative study, the statistics of the comparison (conservative vs. surgical) and of the correlations (magnitude, direction and probability) among BMI, body image and quality of life or at least the probability level values.

 We thank the reviewer for this comment. The introduction has been adapted accordingly. Changes are marked in red.

Introduction: In this section it is addressed that the evaluation of the quality-adjusted life years (QALY) or disability-adjusted life years (DALY) represent essential tools for efficiency calculation and cost-benefit optimization in today's health care system. But it is not observed in the results, nor in discussion, it is suggested to be reconsidered to indicate the role that the above plays in the study that is presented.

We thank the reviewer for raising this concern. Although this section was only for highlighting the necessity of QoL assessment, the introduction was re-structured.

Results: In statistical analyzes, it is not clear if the authors calculated the regression coefficients or only calculated the determination coefficients (R2), since other indicators of this type of statistical analysis are observed, such as the value of Beta, of the ANOVA, of the probability of error, etc. In this regard, it should be noted that these determination coefficients in all cases are very low (.001 to .110). The authors must provide explanations in this regard (for example, it may be due to mediating variables), which requires greater study.

We thank the reviewer for highlighting this. The statistical analysis was carried out with the help of a statistican. Due to the fact a metric variable (BMI) was assessed a regression analysis was used,

References: From 39 references only 10% are 5 years to date, it is suggested to update some of them.

We thank the reviewer for this comment. Several references were updated.

Reviewer 2 Report

Dear authors,

the following aspect should be edited in the manuscript "Factors influencing quality of life after massive weight loss - What makes the difference?". Numbering of lines are missing in the manuscript.

Minor:

Abstract:

Add more statistical information in results-section

Introduction:

Page 1:

"...overweight is assessed by the body mass index (BMI- kg/m2)" --> m²

"...should only serve as a guideline and is not representative of a person's state of health [6] alone." --> reference after "alone"

Page 2

"Apart from a patient's physical health sta-tus, self-perception and own body image are gaining in importance." --> Reference is missing

Obesity is mainly described, but the study is investigating "massive weight loss" (MWL). Please enhance the introduction more with MWL - especially last 1/4 in the introduction. The link between MWL and QoL and method (cons. vs. surgical) regarding to the aim is not clear. This should be highlighted in the introduction. Generally, shorten the introduction.

Results:

Reported values such as (+/- 0.73) have to be clarify in regard to "standard deviation". The presentation of statistical values must be clear. Please revise within the whole results section. 

Discussion:

"So far, literature only partially reports on the impact/effectiveness of weight reduc-tion as a method health-related quality of life (HRQoL) improvement." --> Reference is missing.

"The health status of a population can further be assessed using the BMI4" --> "BMI4" --> please correct reference format

"Regression analyses statisti-cally confirmed that HRQoL is weakened by a high BMI." Please add reference.

Conclusion:

Conclusion is too short. Which conclusions can be drawn from the commentary and the results? Dear authors, so "What makes the difference?"? Please answer the question given by the title.

Major:

Materials and methods:

Please clarify the selection-process and the distribution of the "platforms etc" you searched (patients events, seminars, social media). The reader should be able to reproduce the study ising the methods described.

Page 3

"Measurement tool": here, results and statistic part are described. 

"Table 3": table order is not correct. Within the brackets "+/-" is missing for SD. Please revise in all tables.

Generally the "Analysis" and "Statistic" part are reported redudant, a clear structure with the most important facts is missing. Furthermore, this section is too long.  I recommend to revise this section by a statistican. 

Page 4:

Please clarify the process of clustering in four subgroups (references?).

Method/Results:

Why did the authors choose non-parametric tests such as Wilcoxon text and Kruskal-Wallis-Test? Are the results not normally distributed? Did the authors check for normal districubution? The authors did statistical analysis on a collective with 460 participants - in this case a normal distribution analysis is not necessary (central limit theorem), and thus no non-parametric statistical test is necessary. Please re-analysis with appropiate parametric-tests.

Overview of patient characteristics (juxtaposition of 2 groups) are missing (age, bmi etc.)

Please add gender-related sub-analysis (descriptive analysis is enough for 17 men) in this section and discuss the results and limitations. This limitation should be integrated to you conclusion

Mostly in the tables p-values are missing; please add p-values and which test was used. 

Figures:

Contrast and presentation of figures are not overseeable. Dont use colors. Exakt p-values are missing within figures; "dots" within the figures are confusing, please remove them. Sometimes german words were used (e.g. operativ, konservativ), please correct.

Regression-Figure: regression values are missing, p-values and significance are missing.

There are 5 tables, please merge them in a reasonable way.

Please merge Fig. 3 - Fig 6 in one figure.

Discussion:

Enhance discussion regarding to gender-related results.

 

Institutional Review Board Statement:

"informed consent on 14th of December 2020". Informed consent from review board statement? Please correct this part. 

 

I recommend to revise the whole results-section by a statistican (statistical description, re-analysis, "statistical" correct presentation of tables and figures). Especially this sections, needs more clear structure. 

Furthermore, i recommend an extensive editing of English language and style (e.g. grammar) by a native speaker.

Author Response

Dear authors,

the following aspect should be edited in the manuscript "Factors influencing quality of life after massive weight loss - What makes the difference?". Numbering of lines are missing in the manuscript.

We thank the editor for this comment. Numbering of lines has been added.

Minor:

Abstract:

Add more statistical information in results-section

We thank the reviewer for highlighting this. All changes have been performed as requested and are marked accordingly.

Introduction:

Page 1: 

"...overweight is assessed by the body mass index (BMI- kg/m2)" --> m²

We thank the reviewer for improving our manuscript.

"...should only serve as a guideline and is not representative of a person's state of health [6] alone." --> reference after "alone"

Thank you for this comment.

Page 2

"Apart from a patient's physical health sta-tus, self-perception and own body image are gaining in importance." --> Reference is missing

We thank the reviewer for this comment- a reference has been added.

Obesity is mainly described, but the study is investigating "massive weight loss" (MWL). Please enhance the introduction more with MWL - especially last 1/4 in the introduction. The link between MWL and QoL and method (cons. vs. surgical) regarding to the aim is not clear. This should be highlighted in the introduction. Generally, shorten the introduction.

We thank the reviewer for sharing this concern. The introduction has been shortened and the last part has been completely re-written. All changes are marked accordingly

Results: 

Reported values such as (+/- 0.73) have to be clarify in regard to "standard deviation". The presentation of statistical values must be clear. Please revise within the whole results section. 

We thank the reviewer for this concern. The results section has been revised.

Discussion:

"So far, literature only partially reports on the impact/effectiveness of weight reduc-tion as a method health-related quality of life (HRQoL) improvement." --> Reference is missing.

 

Thank you for this. The reference has been added.

"The health status of a population can further be assessed using the BMI4" --> "BMI4" --> please correct reference format

The reference format has been changed.

"Regression analyses statistically confirmed that HRQoL is weakened by a high BMI." Please add reference.

We thank the reviewer for this comment. A reference has been added.

Conclusion:

Conclusion is too short. Which conclusions can be drawn from the commentary and the results? Dear authors, so "What makes the difference?"? Please answer the question given by the title.

Thank you for highlighting this. The conclusion section has been completely rewritten and the question raised in the title has been answered.

Major:

Materials and methods:

Please clarify the selection-process and the distribution of the "platforms etc" you searched (patients events, seminars, social media). The reader should be able to reproduce the study ising the methods described.

We thank the reviewer for this major concern. The selection process has been specified and therefore reproducibility should be guaranteed.

Page 3

"Measurement tool": here, results and statistic part are described. 

Thank you for this insightful comment. The paragraph has been rewritten.

"Table 3": table order is not correct. Within the brackets "+/-" is missing for SD. Please revise in all tables.

Thank you for highlighting this. All changes have been performed as requested.

Generally the "Analysis" and "Statistic" part are reported redudant, a clear structure with the most important facts is missing. Furthermore, this section is too long.  I recommend to revise this section by a statistican. 

We thank the reviewer for this insightful comment. The whole paragraph was re-structured and shortened. The Analysis and Statistic parts were brought together to avoid redundancies and revised according to your suggestions.

Page 4:

Please clarify the process of clustering in four subgroups (references?).

We thank the reviewer for this comment. The clustering mechanism has been clarified and “groups A-D; Group A: 0kg to 30kg; Group B: 30kg to 50kg; Group C: 50kg to 70kg; Group D > 70kg” has been added to the analysis section.

Method/Results:

Why did the authors choose non-parametric tests such as Wilcoxon text and Kruskal-Wallis-Test? Are the results not normally distributed? Did the authors check for normal districubution? The authors did statistical analysis on a collective with 460 participants - in this case a normal distribution analysis is not necessary (central limit theorem), and thus no non-parametric statistical test is necessary. Please re-analysis with appropiate parametric-tests.

We thank the reviewer for this concern. All statistical analysis have been performed with the help of a professional statistican. Due to the fact we assume that the data are not parametric and since we are comparing dependent samples we have chosen the Wilcoxon test and the Kruskal-Wallis Test.

Overview of patient characteristics (juxtaposition of 2 groups) are missing (age, bmi etc.)

We thank the reviewer for this comment. Patient characteristics have not been mentioned because grouping was performed by either method of weight loss (group 1 and 2) or by the total weight loss (group A-D). Therefore, giving detailed characteristics of all 6 groups would be beyond the scope of the manuscript.

Please add gender-related sub-analysis (descriptive analysis is enough for 17 men) in this section and discuss the results and limitations. This limitation should be integrated to you conclusion

We thank the reviewer for this insightful comment. The response rate and the distribution between male and female respondents is comparable to similar studies. Due to the fact male respondents only represent 3.7% of participants, no subgroup analysis was performed. This was added to the limitation section.

Mostly in the tables p-values are missing; please add p-values and which test was used. 

We thank the reviewer for raising this concern. All p-values have been added, as well as the test performed.

Figures:

Contrast and presentation of figures are not overseeable. Dont use colors. Exakt p-values are missing within figures; "dots" within the figures are confusing, please remove them. Sometimes german words were used (e.g. operativ, konservativ), please correct.

We thank the reviewer for raising this concern. All german words were corrected. We hope the changes in presentation of figures made them more overseeable.

Regression-Figure: regression values are missing, p-values and significance are missing.

We thank the reviewer for this insightful comment. The p-values are given in the tables attached (Table 3, Table 4). Adding p-values to the figures has been initially performed, but made the figures confusing- therefore this method of presentation has been chosen.

There are 5 tables, please merge them in a reasonable way.

We thank the reviewer for identifying this problem. The tables have been merged accordingly.

Please merge Fig. 3 - Fig 6 in one figure.

See the previous question.

 

Discussion:

Enhance discussion regarding to gender-related results.

We thank the reviewer for this comment. Due to the fact only 3.7% of respondents were male (comparable to other questionnaire based studies) no gender related differences could have been found. This was added to the limitation section.

Institutional Review Board Statement:

"informed consent on 14th of December 2020". Informed consent from review board statement? Please correct this part. 

This part was modified.

I recommend to revise the whole results-section by a statistican (statistical description, re-analysis, "statistical" correct presentation of tables and figures). Especially this sections, needs more clear structure. Furthermore, i recommend an extensive editing of English language and style (e.g. grammar) by a native speaker.

We thank the reviewer for this insightful comment. As stated above, all statistical analysis have been performed with the guidance of a professional statistician. The M&M section has been re-written and re-structured.

Round 2

Reviewer 2 Report

The authors followed the reviewers suggestions and made the paper in a more appropriate shape.