Author's response to reviews Title: Identifying work ability promoting factors for home care aides and assistant nurses Authors: Agneta Larsson (agneta.larsson@ltu.se) Lena Karlqvist (lena.karlqvist@ltu.se) Mats Westerberg (mats.westerberg@ltu.se) Gunvor Gard (gunvor.gard@med.lu.se) Version: 6 Date: 28 November 2011 Author's response to reviews: see over
Dear Editor of BMC Musculoskeletal Disorders Thank you for valuable advice for the development of our manuscript entitled "Identifying work ability promoting factors for home care aides and assistant nurses ". We have revised the manuscript according to your recommendations. We have paid special attention to the comments (reviewer # 2) regarding the theoretical and conceptual framework of the study, and have specified a model in the introduction. Response to issues raised by Reviewer # 2 Kuijer Major compulsory revisions :: We have to be more specific regarding the theoretical and conceptual framework of the study. Suggest that we focus on the dependent variable work ability and its prognostic factors in the two professions and in the group as a whole. :: We agree that work ability and its prognostic factors are the main objective of this research. However, we believe that also self-efficacy is an important variable. The results of the regressions on musculoskeletal wellbeing have however been removed. Specify a theoretical model, preferably also depicted in a figure, based on the existing literature in the introduction that explain why the relevant independent factors and their underlying variables Individual background factors (f.i, age, sex) job characteristics (safety climate, psychosocial job demands) and individual perceptions and practices (degree of personal safety, personal safety behavior) were selected as promoting factors for work ability in home care aides and assistant nurses. What is the proposed strength of the model? Is there a possible hierarchy in promoting factors? Are these the most relevant factors for both jobs? What are the blind spots? :: We have described a theoretical model in the introduction, Page 5 and Figure 1. And we further discuss these questions in the Discussion page 18-19. Provide more information what kind of work in terms of tasks and activities is performed by the care aides and assistant nurses. Does the work really differ that much that is provides a rationale to perform analyses for both groups separately? :: Yes, we believe that it is important to analyse the two groups separately. They share the same work place and perform, on the paper, simliar home care work tasks. Therefore, eventual different patterns in factors contributing to the promotion of work ability and self-efficacy is important knowledge. The groups differ in educational level, and status, which may have implication for the power distribution within work groups, and following their actual working conditions. We have tried to argue for these eventual differences more distinct in the Introduction, page 6.
In the introduction it I stated that the work is often described as being the same. What does the model for work ability do for the group as a whole (n=137) :: we have changed the wording, and removed often described as being the same, as we have rewritten this section. :: Additional files with data on the whole group (n=137)together have been enclosed this submission for you to read. The model for work ability for the group as a whole, to some extent show the same pattern as each profession separately, while some factors, for example the association with seniority adds no explanation for work ability for the whole group. The reason for this is that seniority is positively associated with work ability in the group of care aides, while it is negatively associated in the group of assistant nurses. From our point there is more important to address the differences, that the whole group. We have therefore not included the results of the whole group in this version of the manuscript. We have instead worked on improving the discussion regarding similarities and differences between groups. Minor essential revisions Abstract Why call it a pilot study? :: pilot study has been removed Provide data regarding the response rate and main results :: has been added Be specific in terms: for instance work ability :: has been corrected throughout the manuscript.. Conclusion: Are not formulated in the same manner, in the abstract and at the end Introduction: Provide more detailed evidence for the promoting factors in home care aides and assistant nurses :: more information has been added, at page 6 Aims, and research questions, suggestion promotion factors/ prognostic factors for work ability contribute to/ associated with..? Focus on the third question about work ability for the whole and the groups. :: The aim has been re-written, and the research questions removed. We have decided to focus on work ability in the two professions, but also on self-efficacy as self-efficacy can be an important modifiable factor according to theoretical models and research results.
The result on the whole group are nor presented in the manuscript, but are enclosed in a separate file, for now.. Methods Combining the paragraphs Context and population, procedure, and Ethics. :: these have been combined The paragraph the participants :: has been moved to the result section :: 46% has been added after 137 participants, and the numbers (n= ) have been added Combine Table 1 and 2, place it in the result section, provide data for the group as a whole, and for the professions, one decimal is enough for the 12 variables Test whether the two professions differ on relevant prognostic factors and work ability :: One decimal :: A new table (Table 1) with data for each profession and the p-values (differences between the groups) have been added to the manuscript. :: Data for the whole group are submitted in a separate document :: The previous four tables remain as before, that is, data on each profession, scales, and alphas, and also the univariate- correlations (Tables 2 and 3, and 4 and 5). The correlations are not research questions :: We show these correlations as they are the foundations for the regression analyses. As there are always concerns about what to include on the relatively limited space of an article, we could maybe have these as additional material to the files. The information of the scale ranges and alphas are important to keep. Information about body height, weight, BMI :: no, unfortunately we don t have this information Provide the maximum range and qualitative terms for the range ends for the variables 5-12 :: this information has been added The same headings p 7 and 9 :: Page 7, has been changed to Definitions of prognostic factors and work ability Provide the theoretical range of the scales what high or low score mean are there fixed cut-off points :: The range of scales and the end-points have been further specified, page 8-10.
In the regressions models we analysed the independent variables associations with the dependent variable, which have been corrected in the result section. E.g. page 14, Model 2: Prognostic factors for work ability (not.. for high work ability ). We have not used cut of points in the regressions. Therefor e we have also decided to remove the section about differences between the professions, described in proportions of e.g. high work ability Strong self-efficacy (index value >4.5) was reported by 50% of the care aides and.. Just to not confuse the reader with the use of cut-off points only in this paragraph. Provide on or two examples of questions per variable? :: Wonder if providing examples of 2 questions per variable will take up to much of the space? We will provide these questions in a later stage if requested again. Before, we also need to perform a proper back and forth translation procedure, for the quotes of the questions. The physical job demands : : Were asked for the job as a whole. This had been added on page 9, Physical job demands, meaning the perceived physical exertion required when performing the job as a whole an ordinary working day Why call it musculoskeletal well-being when the questions are about prevalences of experiencing pain? Is it valid to calculate a total ratio score over all body regions? :: we have now explained the measure better, on page 9. :: We call it well-being, as it from the view of promotion health is essential to find measures showing the good side. The scale we used reads that a high score is good, that is little or no musculoskeletal symtoms = well-being. :: Both the measure of physical job demands, and the measure of musculoskeletal well-being reflects overall musculoskeletal health and overall exertion during a working day as a whole. Organisation of data analysis :: Has been rearranges according to your suggestions ( e.g. descriptive of participants was calculated by X the descriptive of prognostic factors and work ability by X to test a priori defined prognostic model for work ability) Results Recommendations regarding organization of results, 1 the results of the participants response rate and personal descriptives, 2 Descriptives of the included prognostic variables, 3 The results of the prognostic model tested for work ability :: the results are now presented in the result section in the (above) recommended order, and in tables 1-5. Regression results for both work ability and self-efficacy is presented, separate for each profession. Model 1 etc. /are the variables dichotomised?
:: The variables are not dichotomized, this has been corrected in the text ( high deleted) Discussion Start with the main outcome variables associated with work ability :: The discussion has been re-worked to emphasize the main outcome Make headings strengths and weakness differences and similarities between home care aides and assistant nurses prognostic factors for work ability,.. :: Headings have been made according to the suggestions Strength and weakness: what might be sources of bias in cross sectional studies, might there be a healthy worker selection effect for certain variables for instance having a relative long experience of working within the home care services? :: We have added more about possible bias on page 20. What is new, or what bind spots have been clarified regarding the theoretical framework for prognostic variables for work ability in the two professions and as a whole? Do we have to change the model? Is there a new hierarchy in variables? Provide the reader with your newly required insights! What kind of interventions are available and proven effective to improve the work ability acting through the statistical significant intermediate variables like musculoskeletal wellbeing? What effect size do you expect for the intermediate variable and the dependent variable work ability based on these interventions? What are the practical implications for the organization or the individual worker to improve the work ability? :: These questions have been discussed on page 18-19. :: We have not calculated the real effect sizes. We instead use the B values, which indicate the difference in response unit per unit change in the independent variable, and have presented a few examples. Conclusion not influenced by.. instead using the term related or associated :: this have been corrected throughout the manuscript Formulate one conclusion in the abstract and in the end :: The conclusion has been reworked and is now the same in the abstract and at the end Table 1 and 2 :: have been combined Specify the header in table 3 and 4
:: the header in the tables have been specified. Results on The whole group :: Results on the whole group are submitted as an extra file, for you to look at. Reviewer # Endresen Reme Discretionary revisions Abstract Increased strain... ref in the paper? :: We have added the reference I the paper. More specific, there is foremost a trend towards increased psycosocial strain, while the physical strain is about equal to earlier years, according to the yearly statistics produced by the Swedish Work Environment Authority. The aim other word than explaining.. identify :: Has been changed to identify Background Method Contrast between job characteristics and individual perceptions and practices. :: It is correct that each one of the measures in this study is individual and subjective perceptions of own resources and the environment. In the method section and in the tables, these have been renamed, basic background factors, job-related factors, and personal resources. :: The sentence in page 16 meant that objective (real ) risks, was reflected in a person s subjective perceptions of risks, according to the reference. This sentence have been removed as a result of that we removed the regressions of musculoskeletal wellbeing. More information of the larger study, what was the aim of that study :: One sentence has been added on Page 8. In summary, the aim of the total project was to promote health and work ability among the home care staff, by identifying areas for improvement of a particular model for participatory risk management in home care services, and implement prioritised changes. This project includes both quantitative and participatory research methods. What information did potential participants receive when recruites etc
:: The information given was about the aim of the total project. The letter specified that the questionnaire focused on the respondent s perceptions of health and work ability, the work place and on managing work and risk factors in relation to workers illnesses or accidents. It was also clarified that the work place meant both the general working environment and the private homes belonging to the clients. Note: This information has not been added to the manuscript yet, maybe there are too many details. Results Rational for choosing to do hierarchical regression analyses as opposite to other methods? :: Hierarchical regressions analyses was chosen as we wanted to be able to study the prognostic value of blocks with independent variables on the dependent variables. The reason was that this analysis suited our priory defined theoretical model. The theoretical model has now also been described in the introduction. The first block with basic variables, sex, age etc are not changeable, the second work-related factors are much under the control of others/the work setting. Then, when adding variables closer to the individual and his/her personal resources, tests whether these personal factors, that can be possible to improve, contributes to the explained variance. The last entered block/s are the most interesting in hierarchical regression, to see if the variables are able to contribute to additional explained variance. We discuss this at page 18, Rationale for deciding to set the significance level to 0.10? : : one sentence added on page 11, We used this significance level because the sample size was relatively low, making it more difficult to reach significance even when clear, practical relationships were present. Discussion Highlight the difference in self-efficacy Point to future research to follow up on this issue! Comment on gender effect on self-efficacy and relate to previous literature :: we have added some more about this interesting issue, page 17. Minor essential revisions: Aim :: The wording in the aim has been changed. Major compulsory revisions Methods:
Bias, non responders, discuss :: discussion about the possible bias and non-responders has been added on page 17 strengths and weaknesses Results: Comment on the statistical power of the study! When the regression models are stratified you end up with a model where n=58 and the number of independent variables are 10. How robust does this make the models? What is the risk of spurious findings etc? :: Yes, we are aware of that, the absolute lowest number of observations per respondent is 5, according to Hair (1998). Comments have been added in the strength and weakness discussion page 21, This research can be considered as an explorative study that has identified possible modifiable factors associated with a better work ability. To verify the results, the model needs to be examined in greater depth in a larger scale investigation. A majority of the associations can however be explained theoretically, which is supporting the findings. In the results use the term Associated instead of influencing :: the term associated is used (instead of influencing), this have been changed through the manuscript Discussion: Associated factors instead of predictors :: Throughout the manuscript, we write associated factors or prognostic factors (not predictors) Reviewer # Mackey Sometimes Overly long sentences 5-6 lines. :: that is true, we have made a few changes. Include Statistical data in the result section in the abtract, p values and R2 data for at least two of the main findings :: the information have been added The participants in the result section :: participants are now described in the results
Label Measurements, page 9 :: The label have been changed, page 9. We decided on Definitions of prognostic factors and work ability Reviewer # Coole Minor essential revisions Spelling typos marked in word file :: thank you, these have been corrected. Not pilot. Were the study intended to be powered? If not, how could you aim to explain predictors? :: No, this was only an explorative study, searching to identify possible important factors for the promotion of work ability and self-efficacy. The wording throughout the manuscript has been changed. We no longer write predictors. What we have studied is associations. :: This research was a total study in one municipality. The wording pilot study remained from an earlier version, trying to show that this research was performed on a small population, and that it would need a future larger scale study to conform the findings. We have no deleted pilot. Describe differences I job tasks aides and assistants :: Information about the similarities (work content) and differences (educational level, status) have been added in the introduction, page 6-7. Define seniority :: we mean that the staff were in post for longer (not senior grade), this have been added in page 8, the section basic background factors, and in the Tables. How representative were the participants of the 18 units surveyed? :: more information about the representativeness has been added in the method discussion, page 20.
Please state that you checked the models for normal assumptions for linear regression there looks as if some data could be skewed. :: information has been added at page 12 Data analysis. Yes, the models were checked for normal assumptions for linear regression. For some variables the data are somewhat skewed, but the measures on skewness and kurtosis was found to be within acceptable limits. Address other possible limitations.. possible bias in recruitment supervisors may not have delivered the questionnaires :: we have added this important reflections, at page 20 methods discussion. Whether revisions med to the measurement tools may have affected validity :: at page 12 data analysis, we have added more information about that we tested the scales, that were found to be reliable and valid for use in the context of home care services. Draft versions of the questionnaire had been tested on representatives for the home care services staff. Principal component factors analyses, and analyses of internal reliability were performed. Use of p value o.10 :: are now explained on page 12 data analysis. We used this significance level for the regressions because the sample size was relatively low, making it more difficult to reach significance even when clear, practical relationships were present. We consider this research as an explorative study. Therefore, we have changed the wordings and do no longer write predictors. Regards, Agneta Larsson, on behalf of the authors