Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The submitted manuscript addresses a timely and relevant issue with important practical implications for the healthcare sector. The research methodology is appropriately designed and is based on the use of the validated Nurse-WIS instrument, which enables the identification of individuals at risk of long-term work incapacity or reduced work ability. The statistical methods are adequately described and include both univariate and multivariable logistic regression analyses, which are appropriate for the objectives of the study.

The interpretation and discussion of the findings are well supported by relevant and up-to-date scientific literature. The authors also provide a transparent discussion of the principal limitations of the study, particularly its cross-sectional design, the potential for selection bias, and the relatively low questionnaire response rate. Overall, the methodological approach and interpretation of the results are presented in a clear and scientifically appropriate manner.

Comments:

Among the key methodological limitations of the manuscript is the relatively low questionnaire response rate (15.6%), which may substantially affect the representativeness of the findings. Although the authors performed a non-response analysis, the potential implications of selection bias should be discussed in greater detail. The cross-sectional study design also precludes establishing causal relationships between the identified factors and the risk of work instability. Therefore, the non-causal nature of the data should be emphasized more explicitly in both the Discussion and Conclusions.

Regarding the measurement of variables, the manuscript provides insufficient information on the psychometric properties of the newly developed instrument used to assess ergonomic knowledge, particularly in terms of reliability, validity, and internal consistency. In addition, the assessment of ergonomic practice is based on subjective self-reported data, which may introduce a risk of social desirability bias and should be acknowledged as a potential source of measurement bias.

As minor comments, the manuscript would benefit from greater terminological consistency, particularly through the uniform definition and use of abbreviations such as WI, LTSL, RWC, and MSDs. 

Author Response

Dear Reviewer,

thank you very much for your extensive review of our manuscript. Your comments helped us to present our research work more transparently and precisely. Thank you for taking the time to comment!

Comments 1: Among the key methodological limitations of the manuscript is the relatively low questionnaire response rate (15.6%), which may substantially affect the representativeness of the findings. Although the authors performed a non-response analysis, the potential implications of selection bias should be discussed in greater detail.

Response 1: 

Thank you very much for this very important point. We added the following paragraph in the discussion section (5.4. Strengths and limitations):

“The non-responder analysis revealed significant differences between responders and non-responders in terms of age, gender, occupation and setting. As these characteristics may be potentially associated with the occurrence of MSDs and the risk of LTSL due to MSDs, it cannot be ruled out that the composition of the study population may have influenced the observed risk estimate. Certain groups may have been over- or underrepresented in the sample studied, meaning that the estimated risk of LTSL due to MSDs may not fully correspond to the risk of the underlying population. The results should therefore be interpreted with caution, particularly with regard to their generalizability.”

Comments 2: The cross-sectional study design also precludes establishing causal relationships between the identified factors and the risk of work instability. Therefore, the non-causal nature of the data should be emphasized more explicitly in both the Discussion and Conclusions.

Response 2: Thank you very much for pointing this out. We have already declared in the discussion section of the manuscript that, due to the study design, no conclusions can be drawn regarding causal relationships between the identified factors and the outcome.

“Our study is a cross-sectional survey; therefore, no conclusions regarding causal relationships can be drawn.”

To further emphasize the non-causal nature of the data, we have replaced the term ‘predictors’ with ‘associated factors’ in the article title. Furthermore, we have replaced terms that suggest a possible causal relationship with terminology more appropriate for a cross-sectional study in the abstract, discussion and conclusion section. Additionally, we have inserted the following sentence to indicate that establishing a possible causal relationship should be the subject of future research:

“Furthermore, as the study design does not allow any conclusions regarding a causal relationship, future studies should be conducted using a longitudinal design.”

Comments 3: Regarding the measurement of variables, the manuscript provides insufficient information on the psychometric properties of the newly developed instrument used to assess ergonomic knowledge, particularly in terms of reliability, validity, and internal consistency. In addition, the assessment of ergonomic practice is based on subjective self-reported data, which may introduce a risk of social desirability bias and should be acknowledged as a potential source of measurement bias.

Response 3: Thank you very much for this helpful comment. The newly developed questions on ergonomic knowledge had not assessed in advance for their psychometric properties. To clarify this point, we have added the following sentence to the methods section:

“The new developed questions have not undergone prior validation.”

As you have correctly pointed out, the lack of prior validation of these questions, as well as the purely subjective information regarding ergonomic practice, may lead to bias. To take these points into account as potential limitations of our study, we have added the following paragraph to the discussion section (5.4. Strengths and limitations):

“Furthermore, the questions relating to ergonomic knowledge and the use of ergonomic techniques in everyday practice were new developed and had not undergone any prior validation. Additionally, the exclusively subjective assessment of one’s own working practices must be taken into account as a further potential cause of measurement bias. Due to a desire to conform to social norms, participants might rate their own working practices more highly than they actually are, in order to avoid any potential negative con-sequences of their statements. The results should therefore be interpreted with caution.”

Comments 4: As minor comments, the manuscript would benefit from greater terminological consistency, particularly through the uniform definition and use of abbreviations such as WI, LTSL, RWC, and MSDs.

Response 4: Thank you very much for this helpful suggestion. We have revised the manuscript throughout to ensure terminological consistency, uniform definition and use of abbreviations, including WI, LTSL, RWC and MSDs.

Reviewer 2 Report

Comments and Suggestions for Authors

Summary: This cross-sectional study examined predictors of long-term sick leave and reduced work capacity among German nurses. The findings showed that a third of nurses are at high risk for work instability, and that older age, shift work, lack of assistive equipment, and less favorable ergonomic practices contributed. This study addressed important issues, but there are some issues to be clarified:

 

1. In the second paragraph of the introduction section, the authors mentioned the low effectiveness of curricular interventions in nursing education. It is unclear whether this study also attempted to address the education issue.
2. Materials and Methods: I suggest adding subtitles such as study population, key measures, predictors, statistical analyses, etc., to aid readability.
3. The key outcome variable of this study was the score of the “Work Instability Scale”, which consisted of 30 statements. It is unclear whether the risk of LTSL or RWC due to MSDs is equivalent to the “Work Instability Scale” score; it is also unclear whether all 30 statements were assessed in the same domain and can therefore be treated as a homogeneous scale. The authors contrast “MSD-related work disability” and “Work Instability” (on page 2, bottom line, and on page 3, first line), but the distinction between these terms is unclear. Throughout the manuscript, the authors use many terms interchangeably (risk of LTSL or RWC due to MSDs, risk for MSD-related LTSL, etc.). The key measure should be clearly defined, and the term should be phrased consistently.
4. Study participants:

• It is confusing why the authors decided to randomly select nurses who had filed insurance claims for uncomplicated commuting accidents, instead of selecting from all insured nursing staff. The authors should justify the representativeness of the study sample by providing information on sociodemographic, geographic, and work-related factors.
• The authors mentioned that “Uncomplicated commuting accidents that are not subject to mandatory reporting occur predominantly by chance and are unlikely to be associated with musculoskeletal complaints before or after the accident.” (p3, 2^nd paragraph). However, I think having a commuting accident is likely to lead to musculoskeletal complaints. The authors should justify this claim.
• Please explain what types of occupations are in the other group (n=60), as shown in Table 1.

5. The results shown in Table 2 and Table 4 appear irrelevant because the authors did not propose corresponding research questions, nor did they discuss existing knowledge or a knowledge gap in the introduction section (page 3, first paragraph).

Author Response

Dear Reviewer,

thank you very much for your extensive review of our manuscript. Your comments helped us to present our research work more transparently and precisely. Thank you for taking the time to comment!

Comments 1: In the second paragraph of the introduction section, the authors mentioned the low effectiveness of curricular interventions in nursing education. It is unclear whether this study also attempted to address the education issue.

Response 1: Thank you very much for the opportunity to clarify this point. The aim of our study was not to evaluate curricular interventions in the education sector, but rather to investigate possible links between ergonomic knowledge and ergonomic practices and the increased risk of long-term sick leave or reduced work capacity due to MSDs. To illustrate this more clearly, we have clarified the research gap:

“However, job-related risk factors, especially ergonomics-related factors, for the risk of LTSL or RWC due to MSDs among nursing staff have not yet been investigated.”

 In addition, we have formulated the second research question more precisely:

“Which ergonomics-related factors are associated with an increased risk of LTSL or RWC due to MSDs?”

Comments 2: Materials and Methods: I suggest adding subtitles such as study population, key measures, predictors, statistical analyses, etc., to aid readability.

Response 2: Thank you for this advice, we structured the materials and methods section accordingly.

Comments 3: The key outcome variable of this study was the score of the “Work Instability Scale”, which consisted of 30 statements. It is unclear whether the risk of LTSL or RWC due to MSDs is equivalent to the “Work Instability Scale” score; it is also unclear whether all 30 statements were assessed in the same domain and can therefore be treated as a homogeneous scale. The authors contrast “MSD-related work disability” and “Work Instability” (on page 2, bottom line, and on page 3, first line), but the distinction between these terms is unclear. Throughout the manuscript, the authors use many terms interchangeably (risk of LTSL or RWC due to MSDs, risk for MSD-related LTSL, etc.). The key measure should be clearly defined, and the term should be phrased consistently.

Response 3: Thank you very much for the opportunity to clarify these points.

All 30 statements of the Nurse-WIS are assessed in the same domain and can therefore be treated as a homogeneous scale. To clarify which individuals, according to the results of the Nurse-WIS, are at risk of LTSL or RWC due to MSDs, we have added the following sentence to the methods section:

„Individuals with a score of 20 or higher on the Nurse-WIS are at risk of LTSL or RWC due to MSDs.”

Furthermore, we have revised the manuscript to clarify the distinction between “MSD-related work disability” and “Work Instability” to ensure consistent terminology throughout. We have replaced the term ‘MSD-related work disability’ with the more accurate term ‘MSD-related incapacity for work’ in order to distinguish more clearly between the two terms.

“Risk factors for MSD-related incapacity for work among nursing staff have been studied repeatedly [2, 21-23]. However, job-related risk factors, especially ergonomics-related factors, for the risk of LTSL or RWC due to MSDs among nursing staff have not yet been investigated.”

The key measure is now clearly defined, and the terminology used to describe the risk of long-term sick leave (LTSL) or reduced work capacity (RWC) due to musculoskeletal disorders (MSDs) has been standardized throughout the manuscript to avoid ambiguity and inconsistent usage.

Comments 4: Study participants:

a) It is confusing why the authors decided to randomly select nurses who had filed insurance claims for uncomplicated commuting accidents, instead of selecting from all insured nursing staff. The authors should justify the representativeness of the study sample by providing information on sociodemographic, geographic, and work-related factors.

b) The authors mentioned that “Uncomplicated commuting accidents that are not subject to mandatory reporting occur predominantly by chance and are unlikely to be associated with musculoskeletal complaints before or after the accident.” (p3, 2nd paragraph). However, I think having a commuting accident is likely to lead to musculoskeletal complaints. The authors should justify this claim.

c) Please explain what types of occupations are in the other group (n=60), as shown in Table 1.

Response 4: Thank you very much for the opportunity to explain the points you raised regarding the study participants.

 a) It is not possible to select a sample from all persons insured with the BGW, as the BGW only becomes aware of the insured individuals once they report a suspected occupational disease or a work-related or commuting accident. To explain the rationale behind this sampling frame, we have added the following paragraph to the Methods section:

“Statutory accident insurers in Germany are only aware of their insured individuals once they report a work-related or commuting accident, or a suspected occupational disease. Therefore, it was not possible to randomly select the study population from the total group of all nursing staff insured by the BGW. To the best of our knowledge, there is no characteristic of employees that increases the likelihood of a minor non-reportable accident; therefore, we consider this method to be a sound approach for obtaining a representative sample of BGW policy-holders.”

To the best of our knowledge, there is no characteristic of employees that increases the likelihood of a minor non-reportable accident; therefore, we consider this method to be a sound approach for obtaining a representative sample of BGW policyholders.

The data on sociodemographic and work-related factors of the target population have been taken into account in the non-responder-analysis. Further information about the target population have not been available.

b) As you correctly noted, an uncomplicated traffic accident can result in complaints in the musculoskeletal system. A complaint refers to physical or mental discomfort or pain. What we actually wanted to address in this section is the low probability that such an accident will lead to musculoskeletal disorders. A disorder is a condition that represents a deviation from a healthy physical or mental state. Often, a diagnosis has been made. To clarify this point, we have replaced the term “complaints” with “disorders” in line 111.

c) The group “other occupational groups” listed in Table 1 comprises, on the one hand, theatre nurses and, on the other hand, specialist nurses with additional qualifications in various specialist areas. As these persons have additional responsibilities alongside their nursing duties, we did not wish to include them in the overall group of nursing staff but to present them separately. As these groups also have direct contact with patients and are exposed to the associated physical strain, we believe they belong in the target group for our survey.

Comments 5: The results shown in Table 2 and Table 4 appear irrelevant because the authors did not propose corresponding research questions, nor did they discuss existing knowledge or a knowledge gap in the introduction section (page 3, first paragraph). Response 5:  Thank you very much for this valuable comment. We agree that the relevance of the results presented in Tables 2 and 4 was not sufficiently established in relation to the research questions and the background provided in the introduction. We have therefore revised the manuscript to improve the focus and coherence of the presentation. We have clarified the research gap and formulated the second research question more precisely (Please see also our explanations in # 1). Furthermore, we have included the descriptive data on the ergonomics-related variables in sample description in Table 1 and the accompanying text, as the aim of the study was to investigate the influence of various ergonomics-related variables on the dependent variable in the methods section. Additionally, we have removed Table 4 and the accompanying text entirely from the manuscript, as it was not sufficiently established in relation to the research questions.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for revising the manuscript. I have no further questions.