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Work-Related Musculoskeletal Disorders among Dentists in the United Arab Emirates: A Cross-Sectional Study

Medicina 2022, 58(12), 1744; https://doi.org/10.3390/medicina58121744

by Amal Hussein¹

, Mahmoud Mando^2,3,*

and Ricardas Radisauskas^4,5

Reviewer 1:

Ravi Shankar Reddy

Reviewer 2:

Mangesh Prashant Joshi

Reviewer 3:

Jonhatan Magno Norte Da Silva

Medicina 2022, 58(12), 1744; https://doi.org/10.3390/medicina58121744

Submission received: 7 August 2022 / Revised: 23 November 2022 / Accepted: 23 November 2022 / Published: 28 November 2022

(This article belongs to the Section Epidemiology & Public Health)

Round 1

Reviewer 1 Report

Reviewer Comments

Thank you very much for the opportunity to review the manuscript submission entitled: Work-related musculoskeletal disorders among dentists in the United Arab Emirates: a cross-sectional study.

The current paper aims to at evaluating the frequency of musculoskeletal disorders and their associated sociodemographic and work environment risk factors among dentists in the United Arab Emirates. The data is interesting and it has a relevant rationale, however, some limitations and constructive comments are pointed out below:

General comments:

- The article requires a thorough review of the English language.

Specific comments

Title and Abstract

· Use MeSH terms as keywords.

Introduction

· There are studies which evaluated musculoskeletal disorders among dentists in the United Arab Emirates, but you say the health of dentists in the United Arab Emirates (UAE) has not been fully explored. This is not justifiable. Refer to the following studies.

o Al-Rawi, N.H., Khatib, H.E., Rajoub, L., El-Sayed, M., Naji, R., Youssef, R. and Kawas, S.A., 2016. Work-related Musculoskeletal Pain among Different Dental Specialists in United Arab Emirates. The journal of contemporary dental practice, 17(8), pp.639-644.

o Mando, M., 2022. Work Related Musculoskeletal Disorders Among Dentists in the United Arab Emirates: A Cross Sectional Study.

o Sarwar, S., Khalid, S., Mahmood, T., Jabeen, H. and Imran, S., 2020. Frequency of Neck and Upper Extremity Musculoskeletal Disorders in Dentists. Journal of Islamabad Medical & Dental College, 9(3), pp.207-211.

o Hashim, R. and Al-Ali, K., 2013. Health of dentists in United Arab Emirates. International Dental Journal, 63(1), pp.26-29.

· Please review and scientific background and rationale for the investigation needs to be emphasized

Methods

· All the methods section should be discussed in detail.

· The inclusion/exclusion criteria should be mentioned in detail. Give the eligibility criteria and the sources and methods of selection of participants

· Describe any efforts to address potential sources of bias

Sample size

· I see you mentioned the minimum sample size needed to conduct this study was 393 dentists but the actual sample is just 179. This is not justifiable.

Discussion

· Give a cautious overall interpretation of results considering objectives, limitations, the multiplicity of analyses, and results from similar studies.

· Discuss the generalizability (external validity) of the study results.

Author Response

Reviewer 1:

Introduction

There are studies which evaluated musculoskeletal disorders among dentists in the United Arab Emirates, but you say the health of dentists in the United Arab Emirates (UAE) has not been fully explored. This is not justifiable. Refer to the following studies.

o Mando, M., 2022. Work Related Musculoskeletal Disorders Among Dentists in the United Arab Emirates: A Cross Sectional Study.

o Hashim, R. and Al-Ali, K., 2013. Health of dentists in United Arab Emirates. International Dental Journal, 63(1), pp.26-29.

Please review and scientific background and rationale for the investigation needs to be emphasized

The authors would like to first thank reviewer 1 for the valuable suggestions and comments. We agree that few other studies have investigated the prevalence of musculoskeletal disorders among dentists in the UAE. The authors have revised the suggested publications and accordingly revised the scientific background of the current study. The suggested studies are now cited in the revised manuscript and the rationale for the study investigation has been now emphasized. (Please note that the second paper suggested is our current study).

Two studies investigated the WMSDs among dentists in the UAE. The first one by Al Rawi et al. considered pain as the only symptom of WMSDs without paying attention that WMSDs have other symptoms such as tingling, stiffness, burning, numbness, discomfort, and fatigue (despite the fact that these symptoms are mentioned in the modified version of the Standardized Nordic musculoskeletal questionnaire).

The same thing was considered in the second study by Hashim et al.

The third study by Hashim et al. investigated the general health of dentists without mentioning anything about WMSDs.

All these papers were added to the discussion part.

Methods

All the methods section should be discussed in detail.

The method section was expanded and more details regarding requiting of participants were added.

The inclusion/exclusion criteria should be mentioned in detail. Give the eligibility criteria and the sources and methods of selection of participants.

Sources and methods of selection of participants were added to the method section. Furthermore, the inclusion and exclusion criteria were elaborated.

Describe any efforts to address potential sources of bias and all possible forms of biases.

This was added to the discussion section.

Sample size

I see you mentioned the minimum sample size needed to conduct this study was 393 dentists but the actual sample is just 179. This is not justifiable.

AUTHORS’ RESPONSE:

The authors would like to thank you for your comment. Eligibility criteria has been further explained under the methods section. The authors have now stated the small size as a study limitation. Other limitations have been addressed as well under the Discussion section. Please see the additions/modifications made on lines 325-336.

Discussion

Give a cautious overall interpretation of results considering objectives, limitations, the multiplicity of analyses, and results from similar studies.

The interpretation of results in relation to our objectives were more elaborated in the discussion section. More limitations of the study were mentioned in the discussion section. Other studies concerning musculoskeletal disorders among dentists in the UAE were added to the discussion

Discuss the generalizability (external validity) of the study results.

The authors acknowledge that the final sample size used in this study was smaller than the minimum required sample size that was calculated and stated under the methodology section. The authors are aware that this is a study limitation that could affect the generalizability of the study findings. This limitation has been added under the discussion section which included a recommendation for considering bigger sample size in future studies. The following additions/modifications were made (and highlighted in yellow) under the discussion section to address this point:

“This study has a few limitations that are mainly related to its research methodology. The actual number of study participants, 179, was much lower than the calculated minimum needed sample size (323). The small sample size is a potential threat to the external validity of the study results. Another limitation in this study is related to its the low response rate in the present study (36%) which highlights the drawbacks of responder bias when collecting data using an online survey. Therefore, future studies are recommended to collect their data using face-to-face personal inter-views with dentists in order to increase response rate and eventually reach the minimum needed sample size. Moreover, this study is prone to the healthy worker effect bias. An underestimation of the actual prevalence of WMSDs is not unexpected as this may hide the actual prevalence of WMSDs since dentists who received the survey and suffer from WMSDs troubles may fail to report this due to their absenteeism during the data collection period. Another limitation may arise from the cross-sectional nature of the study’s research design of cross-sectional study where causal relationships the causal variables couldn’t not be identified.”

Thank you very much for inviting me to review this article titled “Work-related musculoskeletal disorders among dentists in the United Arab Emirates: a cross-sectional study”.

Reviewer 2 Report

Thank you very much for inviting me to review this article titled “Work-related musculoskeletal disorders among dentists in the United Arab Emirates: a cross-sectional study”.

1. There are studies that evaluated musculoskeletal disorders among dentists in several parts of the world. I am giving a few references in which the same thing was already done.

a. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8551768/

b. https://www.researchgate.net/publication/320965638_Work-related_Musculoskeletal_Pain_among_Different_Dental_Specialists_in_United_Arab_Emirates

c. https://pubmed.ncbi.nlm.nih.gov/35592521/

d. https://www.contempclindent.org/article.asp?issn=0976-237X;year=2011;volume=2;issue=4;spage=308;epage=312;aulast=Shaik

e. https://bmcmusculoskeletdisord.biomedcentral.com/articles/10.1186/s12891-022-04998-3

f. https://www.sciencedirect.com/science/article/pii/S0020653920332081

g. https://research.ajman.ac.ae/pdf/publisher-pdf-fulltext-prevalence-of-postural-musculoskeletal-symptoms-among-dental

2. Minimum required sample size is not taken in the study.

3. English and grammar at places need to be corrected. In many places Capitalizing the First letter after a full stop is not followed.

4. “The minimum sample size needed to conduct this study was calculated using the Cochrane formula for calculating sample size in cross-sectional studies.” Reference needed

5. Some things are elaborated unnecessarily like “To preserve confidentiality, data obtained from participants were stored in the principal investigator's office and co-investigators personal laptops. Only the investigators had access to the collected data”

6. If possible, result representation can be improved.

7. Novelty in research is somewhat lacking.

Author Response

There are studies that evaluated musculoskeletal disorders among dentists in several parts of the world. I am giving a few references in which the same thing was already done.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8551768/
https://www.researchgate.net/publication/320965638_Work-related_Musculoskeletal_Pain_among_Different_Dental_Specialists_in_United_Arab_Emirates
https://pubmed.ncbi.nlm.nih.gov/35592521/
https://www.contempclindent.org/article.asp?issn=0976-237X;year=2011;volume=2;issue=4;spage=308;epage=312;aulast=Shaik
https://bmcmusculoskeletdisord.biomedcentral.com/articles/10.1186/s12891-022-04998-3
https://www.sciencedirect.com/science/article/pii/S0020653920332081
https://research.ajman.ac.ae/pdf/publisher-pdf-fulltext-prevalence-of-postural-musculoskeletal-symptoms-among-dental

The same thing was considered in the second study by Hashim et al. (only dental students)

The third study by Hashim et al. investigated the general health of dentists without mentioning anything about WMSDs.

All these papers were added to the discussion part.

2- Minimum required sample size is not taken in the study.

AUTHORS’ RESPONSE:

3- English and grammar at places need to be corrected. In many places Capitalizing the First letter after a full stop is not followed.

AUTHORS’ RESPONSE:

The English of the paper were checked for any grammar mistakes and corrected accordingly.

4- “The minimum sample size needed to conduct this study was calculated using the Cochrane formula for calculating sample size in cross-sectional studies.” Reference needed

AUTHORS’ RESPONSE:

The reference was added. Thank you

5- Some things are elaborated unnecessarily like “To preserve confidentiality, data obtained from participants were stored in the principal investigator's office and co-investigators personal laptops. Only the investigators had access to the collected data”

AUTHORS’ RESPONSE:

This statement was removed.

Novelty in research is somewhat lacking.

AUTHORS’ RESPONSE:

Thank you for your comment. Additional study limitations were added to the discussion part.

Furthermore, two studies investigated the WMSDs among dentists in the UAE. The first one by Al Rawi et al. considered pain as the only symptom of WMSDs without paying attention that WMSDs have other symptoms such as tingling, stiffness, burning, numbness, discomfort, and fatigue (despite the fact that these symptoms are mentioned in the modified version of the Standardized Nordic musculoskeletal questionnaire).

The same thing was considered in the second study by Hashim et al.

The third study by Hashim et al. investigated general health of dentist without mentioning anything about WMSDs.

All these papers were added to the discussion part.

Reviewer 3 Report

Thank you very much for inviting me to review this article.

The article brings relevant contributions and with some degree of originality. However, some points need to be improved before the article is published in this Journal.

Points with opportunity for improvement for the article are listed:

1- It would be useful to present the formula or mathematical equation used to determine the sample size of this study, as well as to explain its parameters;

2- It is necessary to present the license of the statistical software used;

3- The topic of methods could be better detailed in subtopics, for example: (1) Ethics; (2) Sample and inclusion and exclusion criteria; (3) Data collection instruments; (4) Statistical procedures;

4- It is not clear how the scores related to stress were obtained. Was it through a sum of the answers? Has this procedure been previously validated? By which study?

5- The equation of the regression model used is not shown. There is also no explanation of which are the dependent and independent variables of the regression model.

6- It is important to standardize the way in which the regression model used is cited. I always recommend referring to as binary logistic regression model.

7- It is also necessary to justify the use of this regression model already in the methodology. Because the dependent variable of the model would be up to two symptoms (response equal to 0) and more than two symptoms of WMSDs (response equal to 1)?

8- The final sample of the study is smaller than the minimum sample size calculated in the methodology. Does this not affect the process of inference and generalization of the findings of this research?

9- What is the parameter to classify the BMI in the categories of values presented? Wouldn't the World Health Organization (WHO) classification be more appropriate?

10- The article does not present the results of normality tests. I recommend putting it as a note after the tables in which the normality of the variables was tested.

11- The multicollinearity of the independent variables of the regression model was not tested. The variance inflation factor (VIF) is recommended to ensure the lack of multicollinearity between the independent variables of the regression model. The presence of leverage points (simultaneously influential and inconsistent) was also not observed in the regression model. Such points should be excluded as they interfere in the process of estimating the parameters of logistic regression models.

For a better understanding of question 11, I recommend the study of:

*Bishop et al. (2022) at [https://www.sciencedirect.com/science/article/abs/pii/S0925753522001436]

13- Were factors such as Stress in the work environment and Stress in personal life included in the model as continuous variables? Is this procedure correct?

14- I would recommend building a last model in which non-significant factors are excluded one at a time (from highest to lowest).

Finally, the study needs to bring more limitations:

15- The study did not consider the severity of symptoms, only the number of symptoms.

16- The study did not consider a range of factors that may contribute to WMSDs, such as psychosocial and organizational factors. This should be entered as a limitation.

17- The use of logistic regression is limited by itself, as it does not allow authors to analyze the direct and indirect influence of risk factors on WRMDs. Thus, future studies should choose to analyze the relationship between risk factors and WMSDs through structural equation modeling, for example.

For a better understanding of question 15, 16 and 17, I recommend the study of:

*Bodin et al. (2020) at [https://www.sciencedirect.com/science/article/pii/S0003687020300259]

*Dong et al. (2021) at [https://www.mdpi.com/1660-4601/18/4/1525]

*Souza et al. (2021) at [https://www.sciencedirect.com/science/article/abs/pii/S0169814121001165]

Author Response

Reviwer 3:

Thank you very much for inviting me to review this article.

The article brings relevant contributions and with some degree of originality. However, some points need to be improved before the article is published in this Journal.

Points with opportunity for improvement for the article are listed:

1-It would be useful to present the formula or mathematical equation used to determine the sample size of this study, as well as to explain its parameters;

AUTHORS’ RESPONSE:

The equation was added with parameters explained and reference

2-It is necessary to present the license of the statistical software used;

3- The topic of methods could be better detailed in subtopics, for example: (1) Ethics; (2) Sample and inclusion and exclusion criteria; (3) Data collection instruments; (4) Statistical procedures;

4-It is not clear how the scores related to stress were obtained. Was it through a sum of the answers? Has this procedure been previously validated? By which study?

AUTHORS’ RESPONSE:

Participants were asked to report the level of stress on a scale of 10.

5- The equation of the regression model used is not shown. There is also no explanation of which are the dependent and independent variables of the regression model.

In response to the reviewer’s comment, the following paragraph was added (and highlighted in yellow) in the results section prior to displaying the results of the regression model. In order to identify the significant predictors of having more than two body regions affected by WMSDs, while controlling for potential confounders, a binary logistic regression model was used. The dependent variable was number of regions affected by WMSDs (0= ≤2 body regions and 1= >2 body regions) while the independent variables were the dentist’s age, gender, specialty, type of practice, experience, clinical hours per day, number of patients per day, the use of dental magnification loops, ergonomic dental chair, stress in work environment, and stress from personal life.

6- It is important to standardize the way in which the regression model used is cited. I always recommend referring to as binary logistic regression model.

AUTHORS’ RESPONSE:

The authors consider this a very valid suggestion. Accordingly, the authors now refer to the use of a binary logistic regression model throughout the manuscript to ensure standardization and consistency

AUTHORS’ RESPONSE:

Thank you for your suggestion. The use of the binary logistic regression model is now explained in the methodology section. The following statement was added and highlighted under the methodology -data analysis section : “Binary logistic regression model was performed to identify significant predictors of the dependent variable, number of body regions affected by MSDs. To conduct the regression model, the dependent variable was categorized into two groups, ≤ 2 body regions, and >2 body regions affected by MSDs among dentists. Factors which were statistically significant in the bivariate analysis (p-value <0.05) and those showing a significance level below 0.20 were included in the multivariate logistic regression model”

Title of Table 7 was further modified to reflect the dependent variable and its two categories.

AUTHORS’ RESPONSE:

“This study has a few limitations that are mainly related to its research methodology. The actual number of study participants, 179, was much lower than the calculated minimum needed sample size (323). The small sample size is a potential threat to the external validity of the study results. Another limitation in this study is related to its the low response rate in the present study (36%) which highlights the drawbacks of responder bias when collecting data using an online survey. Therefore, future studies are recommended to collect their data using face-to-face personal inter-views with dentists in order to increase response rate and eventually reach the minimum needed sample size. Moreover, this study is prone to the healthy worker effect bias. An underestimation of the actual prevalence of WMSDs is not unexpected as this may hide the actual prevalence of WMSDs since dentists who received the sur-vey and suffer from WMSDs troubles may fail to report this due to their absenteeism during the data collection period. Another limitation may arise from the cross-sectional nature of the study’s research design of cross-sectional study where causal relationships the causal variables couldn’t not be identified.”

9- What is the parameter to classify the BMI in the categories of values presented? Wouldn't the World Health Organization (WHO) classification be more appropriate?

AUTHORS’ RESPONSE:

The World Health Organization (WHO) classification was used.

10- The article does not present the results of normality tests. I recommend putting it as a note after the tables in which the normality of the variables was tested.

AUTHORS’ RESPONSE:

The assumption of normality of the data pertaining to scale variables was tested prior to selecting the appropriate statistical test analysis. A legend is now added after Table 6 and it states “*The non-parametric test Mann-Whitney U test was used to compare risk factors between private and governmental sectors as the risk factors showed non-normal distribution of data”

AUTHORS’ RESPONSE:

The authors have made sure that before performing the binary logistic regression model, all assumptions of the model were tested and fulfilled. Multicollinearity of the independent variables was tested using the variance inflation factor (VIF<10). In addition, multivariate outliers were also checked for using the Mahalanobis Distance. The methods by which logistic regression assumptions were tested are now added under the methodology section. The following statement was included (and highlighted in yellow):

“Prior to performing the logistic regression model, the assumptions of multicollinearity and multivariate outliers were checked using the variance inflation factor (VIF<10) and Mahalanobis distance, respectively.”

For a better understanding of question 11, I recommend the study of:

*Bishop et al. (2022) at [https://www.sciencedirect.com/science/article/abs/pii/S0925753522001436]

13- Were factors such as Stress in the work environment and Stress in personal life included in the model as continuous variables? Is this procedure correct?

AUTHORS’ RESPONSE:

Thank you for your comment. Participants were asked to report the level of stress on a scale from 0 to 10.

14- I would recommend building a last model in which non-significant factors are excluded once at a time (from highest to lowest).

AUTHORS’ RESPONSE:

Finally, the study needs to bring more limitations:

15- The study did not consider the severity of symptoms, only the number of symptoms.

16- The study did not consider a range of factors that may contribute to WMSDs, such as psychosocial and organizational factors. This should be entered as a limitation.

For a better understanding of question 15, 16 and 17, I recommend the study of:

*Bodin et al. (2020) at [https://www.sciencedirect.com/science/article/pii/S0003687020300259]

*Dong et al. (2021) at [https://www.mdpi.com/1660-4601/18/4/1525]

*Souza et al. (2021) at [https://www.sciencedirect.com/science/article/abs/pii/S0169814121001165]

AUTHORS’ RESPONSE:

Thank you for your comments and articles. All these limitations were added to the study.

Round 2

Reviewer 1 Report

The authors have addressed all of my comments for this paper, and the present version of the manuscript can be accepted.

Author Response

Thank you for your comments

Reviewer 2 Report

Dear author,due to no new knowledge addition to the science, I feel this manuscript needs to be rejected.

Author Response

Thank you for your comments

Reviewer 3 Report

The authors made an effort to answer all the questions posed by this reviewer.

Some minor elements have not been modified sufficiently. But, this is not something that detracts from the general merit of the article. The authors clearly state the limitations of the article, leaving good suggestions for future work.

This reviewer would suggest just citing some reference when commenting on the use of structural equation models. I suggested the articles by Bodin et al. (2020), Dong et al. (2021) and Souza et al. (2021) for being recent and aligned, to some extent, with the theme of the article.

Author Response

Thank you so much for your comments. These references were cited.

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