An Office Ergonomics Quasi-Experimental Field Study: Interim Results

1. An Office Ergonomics Quasi-Experimental Field Study:Interim Results I�d like to mention that I consider it a privilege to be a member of this team, and I am very grateful to have been asked to present this paper to you today.I�d like to mention that I consider it a privilege to be a member of this team, and I am very grateful to have been asked to present this paper to you today.

2. Sources of Support

3. Research Team

4. The Interventions Highly-adjustable ergonomic chair: Benefits come from chair adjustability and design features State-of-the-art ergonomic training: Helps users get the most out of their chairs Chair & Training and Training-only groups equally maximize the ergonomics of their overall work station

5. The Model of Change

6. Study Timeline

7. Primary Health Outcome Research Hypotheses Over the work week and the work day... participants receiving office ergonomics training will have reduced MS symptom growth relative to control group participants receiving an ergonomic chair as well as ergonomic training will have reduced MS symptom growth relative to the training-only group and control group I will begin with presenting the primary research hypotheses for this part of the study. These are�that [read slide] So, if this red line were to represent the =expected baseline symptom growth= for =everyone= in the study over the work week =or the work day=, then post-intervention we would expect this trend would stay the same for the control group, decrease some for the group receiving the training, and decrease still more for the group receiving both the training and the ergonomic chair. I will begin with presenting the primary research hypotheses for this part of the study. These are�that [read slide] So, if this red line were to represent the =expected baseline symptom growth= for =everyone= in the study over the work week =or the work day=, then post-intervention we would expect this trend would stay the same for the control group, decrease some for the group receiving the training, and decrease still more for the group receiving both the training and the ergonomic chair.

8. Construction of the Bodily Pain Measure This is a representation of the survey the participants asked to fill out three times a day. There is a figure to guide the workers as well as words to describe the different body parts for which we would like them to report on the level of pain or discomfort they are feeling at that time. Specifically these are the [LIST BODY PARTS]. The participants are asked to rate their pain or discomfort on each of these 9 body parts, on a scale of 0 through 10. In these preliminary analyses we are using an outcome measure that sums the level of pain/discomfort across all body areas. Therefore, the raw outcome score can theoretically vary from 0 (if no discomfort was felt in any body area) to 90 (if extreme pain or discomfort is felt in all body areas).This is a representation of the survey the participants asked to fill out three times a day. There is a figure to guide the workers as well as words to describe the different body parts for which we would like them to report on the level of pain or discomfort they are feeling at that time. Specifically these are the [LIST BODY PARTS]. The participants are asked to rate their pain or discomfort on each of these 9 body parts, on a scale of 0 through 10. In these preliminary analyses we are using an outcome measure that sums the level of pain/discomfort across all body areas. Therefore, the raw outcome score can theoretically vary from 0 (if no discomfort was felt in any body area) to 90 (if extreme pain or discomfort is felt in all body areas).

9. Bodily Pain Symptom Data Collection At 2 and 1 months pre-intervention, and at 2, 6 and 12 months post-intervention, participating workers were asked to report symptoms 3x per day, over the course of 1 business week. If a worker completed >80% of the diaries they were not asked to complete a second week. 80% was used as a criterion for examining trends over the week. We include all data completed during this two week period. Maximum of 30 measures per data collection period or a total of 150 measures/individual during the study. I am presenting the preliminary results we obtained up through two months post-intervention. At that time, we had a maximum of 45 measures/participant--because participants were asked to report any pain or discomfort symptoms three times a day ([POINT]: beginning, middle, and end), for a full business week ([POINT] Monday through Friday), at [POINT] 2 and 1 months pre-intervention, and at 2 months post-intervention. I am presenting the preliminary results we obtained up through two months post-intervention. At that time, we had a maximum of 45 measures/participant--because participants were asked to report any pain or discomfort symptoms three times a day ([POINT]: beginning, middle, and end), for a full business week ([POINT] Monday through Friday), at [POINT] 2 and 1 months pre-intervention, and at 2 months post-intervention.

10. Summary of Bodily Pain Data [Point. Loss people who were not reporting a lot of diaries[Point. Loss people who were not reporting a lot of diaries

11. No MS Symptom Increase Over the Week Only The Day When the baseline information came in, we confirmed that symptoms do indeed increase over the day. However, we were surprised to see that symptoms do not perceptibly increase over the week. In this figure, mean rescaled discomfort scores are presented over time. Each point represents a time of day (beginning, middle and end), and each set of three points represents a day of the week (Monday through Friday), and the line with the diamond symbol represents means from the week at the first pre-intervention month, and the line with the square symbol represents means from the week at the second pre-intervention month. You can see, there is an increase in discomfort over the day, but not really over the week. That effectively shoots down a set of our hypotheses: we can�t look for a reduction in symptom increases over the week, since at baseline, there is no increase in symptoms over the week! We can however, move forward with testing the hypotheses concerning symptom increases over the workday.When the baseline information came in, we confirmed that symptoms do indeed increase over the day. However, we were surprised to see that symptoms do not perceptibly increase over the week. In this figure, mean rescaled discomfort scores are presented over time. Each point represents a time of day (beginning, middle and end), and each set of three points represents a day of the week (Monday through Friday), and the line with the diamond symbol represents means from the week at the first pre-intervention month, and the line with the square symbol represents means from the week at the second pre-intervention month. You can see, there is an increase in discomfort over the day, but not really over the week. That effectively shoots down a set of our hypotheses: we can�t look for a reduction in symptom increases over the week, since at baseline, there is no increase in symptoms over the week! We can however, move forward with testing the hypotheses concerning symptom increases over the workday.

12. Key Design and Statistical Issues Because random assignment was not done there is a need to statistically adjust for important group differences that may explain observed findings. Because pain can result from many different sources we need to adjust for important predictors of pain. Need to adjust for multiple measurements of bodily pain for the same person. Need to develop an efficient statistical test of the primary hypothesis. [READ SLIDE][READ SLIDE]

13. Approach toStatistical Analysis Multilevel model constructed with individuals specified as level 2 and time points of measurement specified as level 1. Chair and training groups are compared to the control group. Test of primary hypothesis involves a three-way interaction between group, time of day, and phase of the study (pre- or post-intervention). Models are conditioned on significant pre- and post-intervention group differences and important predictors of pain. Analysts blinded to groups in all but final analysis. [READ SLIDE][READ SLIDE]

14. Dealing With Confounders and Covariates Over 30 variables examined. Step 1. Examined covariates for significant pre -intervention group differences. Step 2. Examined covariates for significant post-intervention group differences. Step 3. Examined covariates for significant prediction of bodily pain. Step 4. Examined correlation matrix of covariates to identify �redundant� variables. Step 5. Examined confounders satisfying above criteria in a multivariate model to assess significant contribution to model fit. [READ SLIDE][READ SLIDE]

15. Final Confounders and Covariates Self-reported repetitiveness of work for hands/wrists (0-6, 6 more repetitive) Self-reported social support from co-workers and supervisors (0-8, 8 more support) Self-reported freedom of distractions from noise in the office (1-6, 6 less distraction) Self-reported health (1-5, 5 poor health) Job level from administrative data (1-5, 5 highest level) Disability status from administrative data (0-1, disability report filed) [READ SLIDE][READ SLIDE]

16. Sample Exclusion Criteria Part-time employees (N=11). Employees who had filed a workers� compensation claim within the six-months prior to study initiation (N=0). Employees not sitting in their office chair for at least 4 hours per day, on average (N=0). [READ SLIDE][READ SLIDE]

17. Total SamplePre-and-Post Intervention [Point, No change in office conditions of characteristics of the workforce could be found and important because these lack of differences were observed in the context of changing that were happening in the States economy and the in the organization over time.[Point, No change in office conditions of characteristics of the workforce could be found and important because these lack of differences were observed in the context of changing that were happening in the States economy and the in the organization over time.

18. Total Sample vs. Study Groups [READ SLIDE][READ SLIDE]

19. Multilevel Model Predictive Variables And Their Coefficients

20. Chair With Training Reduces Pain Symptom Levels Over the Day This graph illustrates fairly well the trends we were expecting to see. [READ TEXT]. [POINT] This is the chair and training group line, with the box symbol�which separates from the other two lines post-intervention. You can also see there might be a reduction in the slope of the line here as well, compared to the training-only and control groups�remember, it is a reduction in that slope which is the test of our main hypotheses. Could say the leap chair stops pain and maintains worker comfort over the workday 12 months after installationThis graph illustrates fairly well the trends we were expecting to see. [READ TEXT]. [POINT] This is the chair and training group line, with the box symbol�which separates from the other two lines post-intervention. You can also see there might be a reduction in the slope of the line here as well, compared to the training-only and control groups�remember, it is a reduction in that slope which is the test of our main hypotheses. Could say the leap chair stops pain and maintains worker comfort over the workday 12 months after installation

21. Recap The lack of symptom growth over the work week was an unexpected finding. The chair-and-training group showed a marked decrease in symptom level and symptom growth post-intervention; this decrease was statistically significant relative to the control group. In case needed: anova BPor group / HWOID|group DAYPART group*DAYPART if dayofwk==1, repeated(DAYPART) Statistical significance for the modification of the �symptom growth over the day� effect was obtained Monday, Tuesday, and Friday in month 3�for technical reasons that was the best I could do to test the hypotheses using repeated-measures ANOVA. I don�t really want to let that be the answer to our hypotheses though, because I�m using a 4-cylinder engine instead of the V-8 we really need to model our data appropriately. In case needed: anova BPor group / HWOID|group DAYPART group*DAYPART if dayofwk==1, repeated(DAYPART) Statistical significance for the modification of the �symptom growth over the day� effect was obtained Monday, Tuesday, and Friday in month 3�for technical reasons that was the best I could do to test the hypotheses using repeated-measures ANOVA. I don�t really want to let that be the answer to our hypotheses though, because I�m using a 4-cylinder engine instead of the V-8 we really need to model our data appropriately.

22. Preliminary Conclusions The Leap chair with training significantly reduces musculoskeletal symptom growth over the work day compared to workers not sitting in a Leap chair and workers who did not receive any training. The Leap chair�s effect persists twelve months after being introduced. If musculoskeletal injuries are the result of cumulative traumas, and pain is an indicator of acute trauma, the Leap chair should reduce the incidence of musculoskeletal injuries in office workers There is a suggestion of a training effect, but the small sample size prevents any conclusions from being made at this time. In case needed: anova BPor group / HWOID|group DAYPART group*DAYPART if dayofwk==1, repeated(DAYPART) Statistical significance for the modification of the �symptom growth over the day� effect was obtained Monday, Tuesday, and Friday in month 3�for technical reasons that was the best I could do to test the hypotheses using repeated-measures ANOVA. I don�t really want to let that be the answer to our hypotheses though, because I�m using a 4-cylinder engine instead of the V-8 we really need to model our data appropriately. In case needed: anova BPor group / HWOID|group DAYPART group*DAYPART if dayofwk==1, repeated(DAYPART) Statistical significance for the modification of the �symptom growth over the day� effect was obtained Monday, Tuesday, and Friday in month 3�for technical reasons that was the best I could do to test the hypotheses using repeated-measures ANOVA. I don�t really want to let that be the answer to our hypotheses though, because I�m using a 4-cylinder engine instead of the V-8 we really need to model our data appropriately.

23. Next Steps We will confirm the assumed underlying model of any intervention effect by demonstrating reduced muscle loading with the ergonomic chair. Examine other health outcomes to explore consistency of effects for a range of health outcomes. Include RULA and OEA as pathway effects.

24. Potential Criticisms Lack of randomization Solved with larger sample and more robust statistical control of pre-intervention differences. Lack of clinically meaningful differences. Solved with larger sample and body-site specific changes over time associated with the chair design. Also addressed with nested studies showing changes in muscle loads. The control group had worse health at baseline We statistically control for pre-intervention differences. Additionally, with other sites these differences will diminish.

25. Potential CriticismsContinued Effects not reproducible across employers Solved with additional companies where observe same effect. You cannot rule out a Hawthorne Effect. True, but we can demonstrate the impact of the chair on biomechanical load changes. Differences due to training not chair (absence of chair only group) Only solved with fourth group if goal to specify chair only effect � IS THIS REAL! Also biomechanical loads study� will demonstrate chair effects. Note how does the training group affect our ability to disentangle the Hawthorne effect. There seems to be some concern about the Hawthorne effect. The Hawthorne effect results when attention to a group and not the specific intervention improves productivity. The goal in the Hawthorne study was to improve productivity through greater illumination. But it was equally plausible that attention by administration of the workers could have produced the desired effect. Thus the question is what do you do from a design perspective to address this problem. To address these we did three things. We implemented a training group to give people attention, but technically this would also change their ability to manage their workspace so it is not a true comparison group. It would need to be a group with a new chair that does not change their ergonomic conditions � in essence the chair would be a placebo. However, we have a group that did not receive any attention so that serves as a basic control group. All we can really do is show that the biomechanical loads are present in the chair group and not in the control group. Note how does the training group affect our ability to disentangle the Hawthorne effect. There seems to be some concern about the Hawthorne effect. The Hawthorne effect results when attention to a group and not the specific intervention improves productivity. The goal in the Hawthorne study was to improve productivity through greater illumination. But it was equally plausible that attention by administration of the workers could have produced the desired effect. Thus the question is what do you do from a design perspective to address this problem. To address these we did three things. We implemented a training group to give people attention, but technically this would also change their ability to manage their workspace so it is not a true comparison group. It would need to be a group with a new chair that does not change their ergonomic conditions � in essence the chair would be a placebo. However, we have a group that did not receive any attention so that serves as a basic control group. All we can really do is show that the biomechanical loads are present in the chair group and not in the control group.

26. The Model of Change

30. Field is wide open for a study that � 1) uses experimental design (control group) 2) examines impact of ergonomic interventions on productivity while people are still on the job, not just lost work days what is the cost to employers of low-level, chronic pain? 3) examines impact of ergonomic interventions on people with �normal� pain levels is it cost-effective for employers to reduce chronic pain using ergonomic interventions?

31. Study Objectives To demonstrate the health, quality of work life, and economic impacts of two office ergonomic interventions Seating (highly adjustable ergonomic chairs) Cost: $1000/participant Office Ergonomics Training Cost: $200/participant Firm is a government tax collection agency

32. SF-36 Pain Score Gold Standard in health field, widely accepted as a valid instrument Two questions: �During the past 4 weeks, how much did pain interfere with your normal work?� �How much bodily pain have you had during the past 4 weeks?� National norms are available for this pain measure