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Work 48 (2014) 471–484 DOI 10.3233/WOR-141916 IOS Press

Effectiveness of computerized risk assessment system on enhancing workers’ occupational health and attitudes towards occupational health Wan-Yi Hoa , Connie Y.Y. Sungb , Qiu-Hua Yua and Chetwyn C.H. Chana,∗ a

Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, China Department of Counseling, Educational Psychology and Special Education, College of Education, Michigan State University, East Lansing, MI, USA

b

Received 13 August 2012 Accepted 14 February 2014

Abstract. BACKGROUND: Efforts have been paid to lower the health risks associated with use of computers at the workplace. Computerized risk assessment systems are available in the market for adoption by companies. OBJECTIVES: The Display Screen Equipment Risk Assessment and Management System was designed for conducting risk assessment and providing intelligent-driven solutions for DSE-related occupational health problems. This report summarizes two consecutive research work conducted on evaluating its effect in reducing body discomfort and mental fatigue, and enhancing sedentary workers’ occupational health. METHODS: Convenience sampling was adopted to recruit participants (111 participants for Study 1 and 75 participants for Study 2 who were randomly assigned to an immediate or a delayed intervention group. The intervention was using DSE RAM System to perform a risk assessment followed by an immediate modification of participant’s workstation based on the recommendations generated by the System. Face to face interview was conducted and participants completed three sets of questionnaires right before the assessment and two weeks after the intervention. RESULTS: The results of Study 1 revealed that the DSE RAM System was effective for alleviating the discomfort and fatigue levels by rectifying the workstation-worker match. These mismatches were identified to be the heights of monitor, keyboard and chair with the workers. The results of Study 2 indicate that the System was specific for promoting participants to take more frequent rest breaks (OR: 3.65) and pay more attention to occupational safety and health information (OR: 3.90). In particular, the take frequent rest breaks behavior was found to predict decrease in discomfort in the eyes and mental fatigue (lack of energy). Nevertheless, there was no strong evidence on the use of the System can lead to immediate attitudinal changes towards occupational health and safety. CONCLUSION: The findings support the notion that workers’ participation and integration of ergonomics into the management are important for successful implementation of occupational health programs. Together with educational and skill training sessions on occupational health at the workplace, the DSE RAM System offers a venue for implementing participatory ergonomics at the workplace. Keywords: DSE RAM system, occupational health, effectiveness, ergonomics

∗ Corresponding author: Chetwyn C.H. Chan, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung

Hom, Kowloon, Hong Kong, China. Tel.: +852 2766 6727; Fax: +852 2330 8656; E-mail: [email protected].

c 2014 – IOS Press and the authors. All rights reserved 1051-9815/14/$27.50 

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1. Background The introduction of computers to the workplace has greatly increased the efficiency of business. At the same time, use of computers was reported to associate with pains and injuries in the upper extremity musculoskeletal system [1]. Sillanpää et al. [2] investigated workers who regularly used display screen equipment (DSE) in their workplaces, and reported a high-prevalence rate (over 16%) of musculoskeletal discomfort in the neck, shoulders, elbow, lower arms and wrists, and fingers. Eklof et al. [3] revealed association between musculoskeletal complaints of workers and the ergonomics and psychosocial risk factors at work. Sung et al. [4] reported that anthropometric match between the workstation and worker was a significant predictor of musculoskeletal discomfort among a group of sedentary workers. In the same study, the mental factors, which related to cognitive factors such as concentration and attention, and accumulative use of DSE was also found to contribute to workers’ musculoskeletal discomfort. Since then, different strategies were developed to attempt to reduce the incidence of musculoskeletal discomfort. For example, one study showed positive effects by launching ergonomics intervention programmes. The prevalence of neck, arm and hand disorders were decreased by about 67% after ergonomic workstation adjustments, longer lunch breaks, improvements in noise and illumination, and improved thermal control of the environment [5]. The results of several studies on implementation of risk assessments also indicated that the use of a standardized assessment procedure was effective for improving the quality and validity of the risk assessment [6,7]. Rule-based recommendations on workstation improvement and other ergonomic features further enhance the workstation-worker match and effectiveness of implementing ergonomic interventions [7]. With all these reasons behind, the design of the Display Screen Equipment Risk Assessment and Management System (DSE RAM System) was motivated which aims to facilitate the administration of risk assessment in the workplace [8]. The System relies on a set of predetermined rules for risk identification based on which recommendations are generated for alleviating the risks associated with improper use of computer workstation [9]. The System operates on a web-based platform which is comprised of five core functions: 1) guide identifying potential hazards related to workstation and task designs; 2) provide rule-based solutions for improving workstation and task designs; 3) archive

assessment records; 4) monitor follow-up reviews for risk control; 5) offer regular occupational health measures and useful self-learning material [8]. Practitioners can operate the System with short training on ergonomics and occupational health. The rule-based algorithm was devised based on various studies on Chinese sedentary workers and other major databases that have been generated by our research team in the past few years [4,10]. Decision rules include age of the worker, existing workstation layout, three misfit indices (monitor height, keyboard and mouse height, and seat height), and worker’s preference of monitor and keyboard positions. For example, two of the rules are: mismatch threshold for monitor-eye level is set between 0 to −4 cm difference, whilst that for keyboardelbow and mouse-elbow is −2 to +2 cm difference [4]. This paper summarizes the research work conducted in two consecutive DSE-related studies: The first study is on evaluating the effectiveness of the DSE RAM System in solving computer work-related problems of sedentary workers. The evaluation parameters include decreasing fatigue and discomfort of computer users and increasing the satisfaction on the modification of their computer workstation. The second one is a follow-up study on exploring the effectiveness of the DSE RAM System in enhancing sedentary workers’ attitudes towards occupational health. Effectiveness was defined as increasing the awareness and positive attitudes towards occupational health in this study.

Study 1 2. Introduction It was reported that risk assessment can be facilitated by use of an interactive, user-friendly computer programme designed with built-in ergonomics assessment capabilities. An effective and comprehensive computerized risk assessment system should be characterized with features that can: 1) identify the potential hazards of the DSE workstation; 2) evaluate the safety and health risks associated with the DSE workstation; 3) assess the DSE workstation with respect to the display screen, input devices, work desk and chair, and accessories such as document holders and footrests. If possible, the system should have a recommendation section that provides useful materials for individuals to further improve their workstation. In view of this, the DSE RAM System was designed and built-in with the above-said characteris-

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tics, therefore it would be reasonable to hypothesize that the System is effective for improving the physical discomfort and mental fatigue of sedentary workers. To evaluate the effectiveness of the rule-based recommendations generated from the DSE RAM System study 1 was carried out to examine the benefits of using the DSE RAM System for solving workstationrelated problems of sedentary workers. Effectiveness in this study was defined as reducing the workers’ musculoskeletal discomfort and fatigue levels, and satisfaction of the workers on the recommendations. The findings would shed light on the validity of the assessment parameters and the recommendations and hence enhance further improvement of the System.

3. Method 3.1. Participants One hundred and eleven participants were recruited from a tertiary education institution in Hong Kong. At the time of the recruitment, the institution underwent a risk assessment exercise for all its staff members (about 1,500 in total). Convenience sampling was used to select the participants. There was similar distribution between male (51.4%) and female (48.6%) participants. The mean age of the participants were 32.7 years (SD = 6.75) ranging from 23 to 54. The job nature of participants included administration (24%), research (30%), academic teaching (8%), clerk (13%), technician (6%), project officer (11%) and others (8%). The mean usage of computer was 2.5 hours (SD = 1.2) and accumulative usage was 7.6 hours (SD = 1.8). All participants either operate computers continuously for four hours or daily accumulation for six hours. Participants were randomized into an immediate or a delay intervention group by means of tossing a coin. After randomization, there were 56 participants received interventions immediately (intervention) and 55 in a delayed (control) condition. No significant differences were found in age, (t(77) = −1.17, p = 0.24), job nature (χ2 (1, N = 101) = 0.09, p = 0.92), and computer usage (cumulative hours) (t(96) = −0.94, p = 0.35) between the two groups. 3.2. Procedures The purposes of the study were first explained to the participant, voluntary written consent was also sought. The researcher and participants were not blinded from

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the interventions which the study group received. A face-to-face interview was conducted with the researcher during which the participants completed the three questionnaires. They were the self-report musculoskeletal discomfort questionnaire, the Chinese Swedish Occupational Fatigue Inventory (SOFI-C) [10], and the DSE satisfaction questionnaire. After completing these questionnaires, the researcher conducted the standardized risk assessment using the DSE RAM System. The assessment procedure was computer-led which covered demographic characteristics, demand and nature of job, computer usage, workstation dimensions and anthropometric measurements, as well as workstation environment including light and noise. After the assessment, the researcher obtained the recommendations generated by the DSE RAM System based on the data. Thereafter, the protocol differed between study and control group. For the study group, which adopted an immediate intervention design, the researcher would make reference to the DSE RAM System generated recommendations and explained them to the participants. The researcher then worked with the participants to carry out the recommendations on site. These might include adjusting height of furniture, rearranging layout of the desktop and providing ergonomic accessories. The whole process took about twenty to thirty minutes. Before the end of the session, the participants were asked to complete a satisfaction toward DSE RAM System questionnaire which solicits feedbacks on the comprehensiveness and usefulness of the DSE RAM System, as well as the recommendations generated. For the control group with delayed intervention, the recommendations generated by the DSE RAM System were presented to the participants after twoweek, and the actual modifications of the workstation and task were carried out at that follow-up session. Participants in both the immediate and delay intervention groups were visited for the second time after two weeks. Similarly, they were asked to complete the same sets of questionnaire during the interview. For participants in the immediate intervention group, they were required to complete an extra of six items, which were on the feasibility of the recommendations and satisfaction towards the interventions delivered by the researchers. For the participants in the delay intervention group, the recommendations generated from the previous assessment were presented and explained. Researcher also carried out the modifications on workstation according to the system generated.

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30%

Percentage

26.46%

27.08%

28.00%

20%

10%

4.62%

4.00% 2.46%

2.46%

Use Glare Filter

Use Headset

3.69%

1.23% 0% Adjust Seat Height

Adjust Screen Height

Use or Adjust Footrest

Change Chair

Re-arrange Desk Space

Adjust Eye Distance

Others

Recommendations

Fig. 1. (Summary of the commonest recommendations prescribed by DSE RAM system.) Examples of Recommendations generated by DSE RAM System. Display Screen: The height of the monitor should be adjusted according to the main recommendations. Use a screen glare filter or an LCD monitor. Input Device (Keyboard, Mouse, Numeric Pad, etc): The height of the keyboard should be adjusted according to the main recommendations. Lower the input devices (i.e. keyboard and mouse) by about __ cm. Make sure there is a gap of at least _ cm between the keyboard and the edge of the desk. Desk: Reorganize the desk surface by removing infrequently used items and placing frequently used items within an 18-inch reach. Clean any obstructing material under the desk, e.g. file clips and storage boxes. Seat: Choose a chair with a stable base and five smooth casters. Choose a chair with scrolled front edges and a padded seat pan. Illumination: Use a desk lamp if additional lighting is required for reading documents.

3.3. Instrumentation 3.3.1. The musculoskeletal discomfort questionnaire The Musculoskeletal discomfort questionnaire is a self-report questionnaire on physical discomfort on nine body parts. Past study has revealed satisfactory sensitivity of identifying pain in the shoulders (100%) and neck (92%) [11]. Participants rated their current discomfort level on a 11-point scales with ‘0’ indicating ‘Not at all discomfort’ and ‘10’ indicating ‘very much discomfort’ on the relevant body parts. The body parts covered by this questionnaire were similar to those used in sedentary workers; studies (e.g. [12,13]). The reliability of self-report questionnaire on pain in neck, shoulders, upper and lower back was found to be between 0.50 and 0.51 (kappa coefficients) [14]. 3.3.2. The Chinese Swedish Occupational Fatigue Inventory (SOFI-C) The original English version was designed by Ahsberg et al. [15]. The participant was required to rate on a 11-point scales, with ‘0’ indicating ‘Not at all’ and ‘10’indicating ‘very high degree’, which reflect

their current extent of fatigue. Domains covered include physical exertion, physical discomfort, lack of energy, lack of motivation and sleepiness. The inventory was translated into Chinese by Leung et al. [10] and its internal consistency of the five domains ranged from 0.88 to 0.90. 3.3.3. The Display Screen Equipment (DSE) Satisfaction Questionnaire This questionnaire is custom-design based on the DSE regulations and guidelines [16]. This questionnaire is used to gather information on the participant’s satisfaction on the layout and setup of the worskstation. There are a total of 25 items which over all essential elements for enhancing healthy use of DSE devices advised by the guideline. The participant was required to rate on a 11-point scale for reflecting the satisfactory level with ‘0’ representing ‘Not at all satisfied’ and ‘10’ representing ‘Totally satisfied’. 3.4. Data analysis The between-group effects on musculoskeletal discomfort, mental fatigue and satisfaction towards DSE

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Table 1 Comparison of musculoskeletal discomfort of participants between the study and control groups

Eyes Neck Shoulders Elbows Forearms Wrists Fingers Upper back Lower back † df

Discomfort scores Mean (SD) Study group‡ Control group‡ Pretest Posttest Pretest Posttest 5.13 (2.56) 3.73 (2.22) 5.82 (2.66) 5.20 (2.49) p-values 5.24 (2.75) 3.84 (2.46) 5.61 (2.77) 5.29 (2.84) p-values 4.91 (2.82) 3.78 (2.59) 5.41 (2.67) 5.43 (2.81) p-values 3.56 (2.50) 2.62 (2.23) 3.91 (2.65) 3.98 (2.44) p-values 3.29 (2.49) 2.47 (2.16) 3.71 (2.53) 4.05 (2.42) p-values 3.80 (2.71) 2.60 (2.21) 4.02 (2.65) 4.09 (2.50) p-values 2.82 (2.60) 2.31 (2.01) 3.11 (2.30) 3.41 (2.16) p-values 4.69 (2.82) 3.22 (2.29) 5.46 (2.54) 5.13 (2.84) p-values 4.35 (2.70) 3.31 (2.49) 4.64 (2.49) 4.57 (2.62) p-values

Between group

F -values† Within group

6.750 0.011 3.704 0.057 5.055 0.027 4.154 0.044 6.193 0.014 4.046 0.047 3.217 0.076 9.579 0.003 3.194 0.077

Interaction

20.460 < 0.001 18.238 < 0.001 7.738 0.006 4.543 0.035 1.237 0.268 6.415 0.013 0.288 0.192 13.166 < 0.001 6.295 0.014

3.000 0.086 7.160 0.009 8.244 0.005 6.150 0.015 7.226 0.008 8.142 0.005 4.503 0.036 5.151 0.025 4.776 0.031

F-values† Within group

Interaction

= 1,109; ‡ Study group = immediate intervention group; Control group = delayed intervention group. Table 2 Comparison of SOFI scores of participants between the study and control groups

PE PD LE LM SL

SOFI scores mean (SD) Study group‡ Control group‡ Pretest Posttest Pretest Postest 1.94 (1.86) 1.57 (1.56) 2.12 (1.75) 2.39 (1.92) p-values 2.72 (2.00) 1.81 (1.55) 3.33 (2.12) 3.08 (2.12) p-values 3.16 (2.26) 2.04 (1.71) 4.31 (2.55) 3.85 (2.41) p-values 2.58 (2.06) 1.92 (1.70) 3.24 (1.93) 3.19 (2.19) p-values 3.14 (2.20) 2.32 (1.87) 4.10 (2.05) 3.85 (2.35) p-values

Between group 2.780 0.098 7.779 0.006 14.000 < 0.001 7.615 0.007 11.339 0.001

0.090 0.762 13.546 < 0.001 22.375 < 0.001 5.757 0.018 10.564 0.002

3.610 0.060 4.225 0.039 3.814 0.053 4.301 0.040 3.047 0.084

† df = 1,109; ‡ Study group = immediate intervention group; Control group = delayed intervention group. Note: PE = Physical Exertion; PD = Physical Discomfort; LE = lack of energy; LM = lack of motivation; SL = sleepiness.

RAM System driven intervention were examined by two-way repeated measure ANOVA. No intention to treat analysis was conducted as there was no drop out throughout the study.

4. Results The results of the DSE RAM System based assessments revealed that 35.6% of the monitor height, 38.4% of the seat height and 32.7% of the keyboard height exceeded the normal range (± 2.0 cm) and therefore required intervention. The mean misfit of keyboard height was +8.8 cm (higher than normal,

SD = 3.4 cm). The mean misfit of monitor height was +6.9 cm (higher than normal, SD = 5.1 cm) and −2.9 cm (lower than normal, SD = 1.5 cm). The mean misfit of seat height was +3.3 cm (higher than normal, SD = 1.6 cm) and −3.6 cm (lower than normal, SD = 1.8 cm). No significant differences were found in the misfit of monitor height (t(71) = 0.8, p = 0.82), keyboard height (t(71) = 1.6, p = 0.11), and seat height (t(71) = 0.21, p = 0.84) between the study and control groups. A total of 325 recommendations were generated from the DSE RAM System for all the participants (Fig. 1). The recommendations specific to the adjustments of heights of the seat and monitor were 26.5% and 27.1% respectively. These two recommen-

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W.-Y. Ho et al. / Effectiveness of computerized risk assessment system Table 3 Comparison of satisfaction with recommendations of participants between ‘high’ versus ‘low’ feasibility groups

MH IH CA

Satisfaction scores mean (SD) More feasibility group Less feasibility group Pretest Posttest Pretest Posttest 7.29(1.54) 7.61(1.17) 6.30(1.33) 6.13(2.18) p-values 6.00(2.37) 7.33(1.51) 5.44(2.83) 5.78(2.28) p-values 6.26(2.19) 6.74(1.58) 5.67(2.18) 5.71(1.95) p-values

Between group

F-values† Within group

Interaction

11.744 0.001 0.838 0.377 2.530 0.119

0.079 0.779 3.145 0.100 0.953 0.334

0.896 0.348 1.132 0.307 0.640 0.428

† df = 1,49 for MH; 1,13 for IH; 1,46 for CA respectively; Note: MH = Height of Monitor; IH = Height of Input Devices; CA = Chair Adjustability.

dations were to address the problems associated with the height misfits of the monitor, keyboard and seat. 4.1. Musculoskeletal discomfort Four out of nine body parts (including shoulders, elbows, wrists and upper back) showed significant difference in musculoskeletal discomfort in both betweengroup (F = 4.05–9.58, df = 1,109, p < 0.050) and within-group (pretest and posttest) comparisons (F = 4.54–13.17, df = 1,109, p < 0.050). The interaction effects were also statistically significant (F = 5.15– 8.24, df = 1,109, p < 0.050) (Table 1). Both eyes and forearms showed significant between-group differences (F = 6.75, df = 1,109, p = 0.011 for eyes; F = 6.19, df = 1,109, p = 0.014 for forearms). Moreover, significance was also found in within-group differences for the eye (F = 20.46, df = 1,109, p < 0.001) but not for forearms (F = 1.24, df = 1,109, p = 0.268). Nevertheless, the interaction effect for eyes was not statistically significant (F = 3.00, df = 1,109, p = 0.086) but significant in forearms (F = 7.23, df = 1,109, p = 0.008). Post-hoc comparisons of the participants in the study group indicated that all mean musculoskeletal discomfort ratings were significantly lowered after the intervention (t(54) = 2.51–5.43, p < 0.006) except the fingers (t(54) = 1.91, p = 0.062). 4.2. Mental fatigue Among the five SOFI-C subscales, two of them including Physical Discomfort (PD) and Lack of Motivation (LM) showed significant difference in both between-group (F = 7.78, df = 1,109, p = 0.006 and F = 7.62, df = 1,109, p = 0.007 respectively) and within-group (pretest and posttest) comparisons (F = 13.55, df = 1,109, p < 0.001 and F = 5.76, df = 1,109, p = 0.018 respectively). The interaction effects were also statistically significant (F = 4.23, df

= 1,109, p = 0.039 and F = 4.30, df = 1,109, p = 0.040 respectively) (Table 2). Furthermore, significant between- and within- group effects were observed in Lack of Energy (LE) (F = 14.00, df = 1,109, p < 0.001 and F = 22.38, df = 1,109, p < 0.001 respectively) and Sleepiness (SL) (F = 11.34, df = 1,109, p = 0.001 and F = 10.56, df = 1,109, p = 0.002 respectively). However, the interaction effects of these two subscales were not statistically significant (F = 3.81, df = 1,109, p = 0.053 for LE; F = 3.05, df = 1,109, p = 0.084 for SL). Post-hoc comparisons between the pretest and posttest SOFI-C scores of participants in the intervention group indicated significant decreases in scores on most subscales at the posttest (t(54) = 3.47–5.10, p  0.001), except the Physical Exertion (t(53) = 1.63, p < 0.110). 4.3. Satisfaction on DSE intervention Since the misfit of the monitor, keyboard and seat heights had the highest frequency and many of the DSE RAM System based recommendations were generated because of these problems, the comparisons of participants’ satisfaction were chosen to be on these three items (Table 3). No significant between- and withingroup differences in the satisfaction ratings were revealed. The interaction effects were also not statistically significant. To further analyse the results, participants in the study group were categorized with respect to their ratings into the ‘high’ and ‘low’ perceived feasibility of the recommendations groups. The mean ratings on the feasibility item were used as the cut off of the ‘high’ versus ‘low’ groups. The participants in the intervention group were divided into the ‘high’ (N = 28, 6, 27 for monitor, input devices, and chair respectively) and ‘low’ perceived feasibility groups (N = 23, 9, and 21 respectively). Significant differences in satisfaction with monitor height were revealed between the ‘high’ and ‘low’

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groups (F = 11.74, df = 1,49, p = 0.001). The withingroup difference and interaction effect were found statistically not significant. The between- and withingroup differences in the satisfaction ratings on the keyboard and mouse height, and chair height were statistically not significant. The interaction effects were also not significant.

5. Discussion Previous studies suggest that physical discomforts and fatigue are common problems to tackle at the workplace [17]. Our findings indicate that the misfits of the monitor, keyboard and chair, and the workers are critical for improving the workstation-worker match. The recommendations generated by the DSE RAM System are specific for tackling the misfit problems. When compared with the control group, participants showed significant decreases in their discomfort and fatigue levels within two weeks after the implementation of these recommendations. The results are supported by other studies such as Ketola et al. [18] and Seghers [19] who reported that monitor and keyboard heights contributed to shoulders and neck discomforts, whereas Liao and Drury [20] identified a mismatch between keyboard and seat height was often compensated by frequent inclination of trunk, backward or forward, may further increases the severity of upper and lower back pain. With these, various authors suggested adjusting the heights to resume a normal sitting posture is an effective method (e.g. [20,21]). Gold et al. [22] explained that non-neutral postures were important contributor of musculoskeletal discomfort. Thus a proper posture, as enhanced by the DSE RAM System, would reduce the strain on the bodily system and hence recuperate the stress-tolerance capacity of the body. This in turn would alleviate the physical fatigue of the workers. An interesting phenomenon observed in this study is that participants in the study group, despite improved discomfort and fatigue, did not largely satisfied with the recommendations. Instead, the satisfaction was found to be influenced by whether the recommendations were perceived as feasible to their working environment and/or work habit. Satisfaction is likely to associate with positive attitudes and to some extent compliance [23–25]. In many instances, the effectiveness of advices depends on one’s accepting and attributes to the needs of perceived feasibility of recommendation, and was finally revealed in terms of satisfaction towards workstation.

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Vink et al. [26] identified several common reasons why workers perceived recommendations as less feasible. First, workers may have different viewpoints on what the ‘problems’ and hence the ‘solutions’ are. For example, the workers may prefer a less dramatic change to the workstation because they are likely to underestimate the misfits between the workstations and their anthropometric characteristics [27]. The results from the risk assessment such as those generated from the DSE RAM System may be perceived as too stringent and overestimated. The consequence is that the workers may not feel comfortable with the changes stipulated by the System. Second, the readiness of the workers to change their existing work habit and workstation layout is an important factor for successful implementation of the recommendation [28]. Changes in behaviour require change in attitudes, which involves specific steps and techniques such as accurate information and experiential contacts (or exposures) [29]. The fact that the implementation of the recommendations did not take into account to this would hamper the participants’ satisfaction. Third, the workers may not have experienced a noticeable change in both discomfort and fatigue levels. Vink et al. [26] commented that very often the workers were used to the discomfort in particularly for those who worked long hours. As a result, the participants did not have the urge to initiate change to their workstation. There are, however, ways to improve the workers’ awareness of the importance of achieving a workstation-worker match. May et al. [24] suggested that education of the workers and involving the workers in the process of decision are crucial to the process, especially on older workers since they physically benefit more slowly than younger workers from interventions. Subsequent to study 1, the findings shed light on the enhancement of the second version of the DSE RAM System.

Study 2 1. Introduction The use of the DSE RAM System prototype was found to be effective for improving physical discomfort and mental fatigue of sedentary workers in Study 1. Nevertheless, the results also suggested that the extent to which the users perceived the recommendations as useful and feasible would largely influence the level of satisfaction toward the recommendations generated by the DSE RAM System. And hence the effectiveness

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of advices seems to depend on one’s acceptance and attributes to the need of perceived feasibility of recommendation. Different from the previous study, the DSE RAM System was further enhanced to be a fullfledged web-based computer program for the use by both the risk assessors and users. The second version of the DSE RAM System has taken the participatory approach by providing substantial information on the ergonomic standards set for various features/components of a workstation. For example, the System displays the links to the appropriate websites of which the workers (or the risk assessors) who use the System can access and browse. The System also has incorporated a joint section to be filled out by the worker together with the risk assessor to integrate the assessment data and users’ preference for the System to come up with more preferable recommendations for workstation changes. The change of one’s behaviour depends largely on whether his attitudes can be modified. If the DSE RAM System is designed for improving workers’ occupational safety and health toward the use of DSE at the workplace, which is a set of desirable behaviour. It would be logical to hypothesize that the System would be able to modify one’s attitudes toward using the DSE at work. According to the theory of reasoned action [30], which applied to explain human behaviours in a variety of decision contexts [31,32], proposed that individual’s behaviour may largely be influenced by personal and social intents. The personal intent refers to attitudes which are further influenced by one’s values and beliefs [29,31]. The social intent refers to the social norms as perceived by that individual, which is the influence by people (social) directly or indirectly towards the thoughts, feelings, and actions of others. Previous studies have shown that attitudinal influence was a stronger factor than social influence on predicting individual’s behaviour [33]. As a result, a follow-up study was conducted to account for the effectiveness of the DSE RAM System on reducing the physical and mental discomfort, possibly, attributed to a change in attitude towards healthy use of computer workstation. The aim of study 2 was to investigate to what extent the DSE RAM System would enhance positive changes in attitudes of workers toward a healthy use of the DSE units after the assessment procedures. The changes in attitudes, if there are any, are expected to account for the positive behavioural changes, as well as the changes in the physical and psychosocial work-related symptoms, and workers’ compliance to the DSE modifications. Apart from what has been defined above, effectiveness was also defined as increasing the awareness and positive attitudes towards occupational health in this study.

2. Method 2.1. Participants Seventy-five sedentary workers were recruited from a major banking corporation in Hong Kong which had installed and operated the System for use. At the time of the recruitment, the DSE RAM System was newly introduced to the departments from which the participants were recruited. The participants were selected based on convenience sampling and the inclusion criteria were workers who used computers continuously for four hours or daily accumulative of six hours, no prior knowledge on use of DSE RAM System. Among the 75 participants (20% male and 80% female), the mean age of the participants were 36.0 years (SD = 7.7), ranging from 25 to 58. The participants represented a variety of job natures, including administrative (12%), clerical (49.4%), technical (37.3%) and others (1.3%).The mean daily accumulative usage was 6.6 hours (SD = 1.7). Participants were randomized to the immediate (study) or delayed intervention (control) groups by means of tossing a coin. After the randomization, there were 38 and 37 in the study and control group respectively. No significant differences were found in the age (t(75) = 1.498, p = 0.139), computer usage (cumulative hours) (t(74) = −0.805, p = 0.424) between the two groups. 2.2. Procedures The procedures adopted in this study were similar to Study 1. The only difference was that the three sets of questionnaires used in this study were the physical discomfort and mental fatigue questionnaire, the computer-specific occupational health attitudes and the behavioural checklists. Similarly, the researcher and participants were not blinded from the interventions which the study group received. 2.3. Instrumentation The self-report musculoskeletal discomfort questionnaire and the Chinese Swedish Occupational Fatigue Inventory (SOFI-C) were the same with those used in study 1. The last one was a computer-specific occupational health attitudes and behavioural checklist. It was custom-designed for this study and had two parts: attitude and behaviour. The attitude section is composed of 14 items which tap on the beliefs and attitudes toward the usability, practicality, perceived im-

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Table 4 Comparison of musculoskeletal discomfort of participants between the study and control groups Discomfort scores mean (SD) Study group‡ Control group‡ Pretest Posttest Pretest Posttest Eyes 3.78 (2.66) 2.69 (2.34) 3.74 (2.51) 3.47 (2.31) p-values Neck 4.20 (3.13) 3.20 (2.42) 4.09 (2.21) 3.26 (2.02) p-values Shoulders 4.25 (3.14) 3.17 (2.58) 4.14 (2.61) 3.40 (2.16) p-values Upper back 3.31 (3.34) 2.81 (2.57) 3.40 (2.44) 2.74 (1.84) p-values Lower back 3.03 (3.15) 2.47 (2.62) 2.80 (2.00) 2.57 (2.02) p-values Musculoskeletal discomfort 17.97 (14.22) 14.05 (11.97) 17.86 (10.47) 15.06 (9.43) index§ p-values

F -values† Between group Within group Interaction 0.49 0.488 < 0.01 0.958 0.01 0.915 < 0.01 0.978 0.01 0.908 0.03 0.047

6.44 0.013 15.02 < 0.001 16.11 < 0.001 6.24 0.015 3.57 0.063 13.44 0.013

2.38 0.128 0.13 0.718 0.56 0.457 0.12 0.736 0.62 0.434 0.37 0.005

† df

= 1,70; ‡ Study group = immediate intervention group; Control group = delayed intervention group. § Musculoskeletal Discomfort Index is the sum of the ratings on discomfort levels in the eye, neck, shoulders, and upper and lower back (the maximum is 50, based on the visual analog scale (VAS), from ‘0’ indicating no discomfort to ‘10’ indicating extreme discomfort).

portance and appreciation of feedbacks made by the DSE System. These factors were identified as having high sensitivity to detect changes in attitudes related to implementation of occupational health interventions [27]. The participant was to rate on a 5-point scale, with ‘1’ indicating ‘Totally disagree’ and ‘5’ indicating ‘Totally agree’ which represents the degree of agreement to the statement [34]. The behavioural section is composed of 15 items and the participant was to report on what had been done against the items in the past two weeks by answering ‘Yes’, ‘No’ or ‘N/A’. The items were selected based on the recommendations generated by the System captured in Study 1. These recommendations were found to be comparable to those reported in other workplace ergonomic intervention studies [21,35]. A few of the examples were adjusting the height of monitor or chair, using footrest and take regular breaks were commonly generated across workplace ergonomic intervention studies.

The results of t-tests indicate non-significant differences in the scores on the three instruments conducted at the baseline (p > 0.05), indicating that the two groups were largely equivalent at the beginning of the study. Power analysis indicates that 33 participants can achieve an 80% power to detect a ± 0.1 differences (SD = 0.3), and alpha = 0.05 (two-tailed) in group mean comparisons. The sample size of the study and control groups can be regarded as adequate for detecting the differences if any.

2.4. Data analysis

3.1. Musculoskeletal discomfort and mental fatigue

The between-group effects on musculoskeletal discomfort and mental fatigue were examined by twoway repeated measure ANOVA. The behavioural and attitudinal changes towards healthy use of computer were compared with odd ratios (ORs) using a 95% confidence interval (95% CI). Multiple regression procedure was conduced to test how attitudinal and behavioural changes would predict occupational health among the workers. The independent variables were the attitudinal and behavioural items which had an odd ratio higher than 1.00 and CI not covering 1.00. The

The discomfort levels of the five items: eyes, neck, shoulders, upper back and lower back were summed to form the total physical discomfort index. Participants in the study group tend to show lower scores than the control group (Table 4). The within-group differences of musculoskeletal discomfort of different body part except lower back between the two assessment occasions were statistically significant (F = 6.24–13.44, df = 1,70, p < 0.05). The between-group and the interactions between the group and assessment occasion were statistically insignificant (p > 0.05). Similarly, partic-

dependent variables were the musculoskeletal discomfort index and subscale scores of mental fatigue. Furthermore, there was no dropout of participants in the study, thus no intention to treat analysis was carried out in the study.

3. Results

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W.-Y. Ho et al. / Effectiveness of computerized risk assessment system Table 5 Comparison of SOFI-C subscale scores of participants between the study and control groups

PE

Study Pretest 1.45 (1.70)

PD

2.20 (2.21)

LE

2.81 (2.52)

LM

1.58 (1.75)

SL

2.37 (2.08)

SOFI scores mean (SD) Control group‡ Posttest Pretest Postest 0.90 (1.21) 1.51 (1.66) 1.46 (1.65) p-values 1.38 (1.61) 2.13 (1.85) 1.73 (1.66) p-values 1.65 (1.79) 2.61 (2.16) 2.12 (1.78) p-values 1.18 (1.37) 1.92 (1.69) 1.83 (1.64) p-values 1.68 (1.58) 2.42 (1.73) 2.14 (1.41) p-values

group‡

Between group 0.82 0.370 0.11 0.739 0.09 0.772 1.83 0.180 0.43 0.512

F-values† Within group 3.76 0.057 13.61 < 0.001 16.92 < 0.001 3.15 0.080 10.42 0.002

Interaction 2.69 0.106 1.63 0.206 2.80 0.099 1.21 0.276 1.78 0.187

†

df = 1,68; ‡ Study group = immediate intervention group; Control group=delayed intervention group. Note: PE = Physical Exertion; PD = Physical Discomfort; LE = Lack of Energy; LM = Lack of Motivation; SL = Sleepiness.

ipants in the study group appeared to have more declines than the control group in score on the five SOFIC subscales (Table 5). Among them, significant withingroup effects were observed in the Physical Discomfort (PD), Lack of Energy (LE), Sleepiness (SL) subscales (F = 13.61, df = 1,68, p < 0.001, F = 16.92, df = 1,68, p < 0.001, and F = 10.42, df = 1,68, p = 0.002 respectively). However, the between-group and interaction effects of these two subscales were also not statistically significant, (p > 0.05). 3.2. Behavioural and attitudinal changes Odd ratios were used to test the differences in occurrence between the two groups. Among a total of 15 behavioural items, there were two which satisfied the criterion of odd ratio value greater than 1.00 with CI not covering 1.00 (Table 6). They were take frequent rest breaks (Item 13) (OR = 3.65) and attend to occupational health information (Item 15) (OR = 3.90). However, the between-group differences in the occurrence of attitudinal changes were not statistically significant (Table 7). 3.3. Prediction of behavioral changes on work-related occupational health The behavioural items 13 (take frequent rest break) and 15 (attend to occupational health information) were entered as independent variable to predict the decrease in the physical discomfort and mental fatigue. Item 13 was found to significantly predict a reduction in Lack of Energy (ß = 0.28, t(73) = 2.46, p < 0.05), whereas item 15 was found to marginally predict a reduction in Sleepiness (ß = −0.31, t(73) = −1.93, p = 0.058). Furthermore, items 13 (ß = −0.08, t(73) =

−2.03, p < 0.05) and 15 (ß = −0.11, t(73) = −2.27, p < 0.05) were found to significantly predict a decrease in the discomfort in the eyes.

4. Discussion The purpose of the present study was to explore the effectiveness of the DSE RAM System for enhancing positive changes in the behaviours and attitudes of workers towards healthy use of computer workstation. The results indicated that the System appears to be effective for promoting changes in healthy behaviours such as taking more frequent rest breaks and paying more attention to occupational safety and health information. However, the System did not seem to enhance workers’ attitudes toward healthy use of DSE. The behavioural changes were associated with decreases in musculoskeletal discomfort and mental fatigue. Participatory ergonomics has been reported as an effective method to enhance occupational health in the workplace [36]. Haslam [37] explained that the benefits are attributable to the fact that changes to be brought about are specific to the workplace and hence directly benefit and easily accepted by the workers. Bohr [38], with the use of participatory ergonomic approach, further reinforced the concept of modification of workplace directly benefit workers and leading to more frequent healthy behaviours. For instance, case studies have reported reductions in musculoskeletal and mental discomfort [7,35] after intervention of participatory programs. The results of this study further support previous findings. They further explained that this was due to an improvement in the workstation’s ergonomic qualities, such as more spacious working desk and provision of equipments such as

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481

Table 6 Odd ratios (study/control) of behavioural changes on healthy use of computer Odd ratios 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

Adjust height of the monitor screen to the eye level. Keep elbow at about right angle when typing on the keyboard. Rest wrist on a wrist support or on the desktop when typing on the keyboard. Adjust height of the mouse to a similar level with the keyboard. Place document holders alongside, at the same height and distance from you, as the screen. Adjust height of office chair to fit the height and sitting posture. Use a cushion to support the back at the waist level. Keep sitting posture upright. Rest the feet on the floor or use a footrest. Rearrange layout of the desktop so as to spare more room for work. Clear-up space underneath the desk so as to have more legroom. Perform stretching exercise regularly at the workplace. Take more frequent rest breaks or increase the duration of each break. Adjust brightness of the workstation or workplace. Attend more frequently to information on occupational safety and health.

1.75 1.10 0.76 1.25 1.17 0.97 0.97 1.46 2.92 0.97 0.49 0.85 3.65 1.56 3.90

95% CI Lower Upper 0.94 3.28 0.47 2.53 0.22 2.60 0.52 3.01 0.39 3.50 0.38 2.51 0.21 4.52 0.26 8.25 0.63 13.56 0.15 6.56 0.13 1.80 0.34 2.11 1.34 9.98 0.56 4.33 1.20 12.69

Table 7 Odd ratios (study/control) of attitudinal change towards healthy use of computer Odd ratios 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

I believe that sharing and support among the workers can help resolve the risks associated with use of computer. An office chair with full arm support is essential for desktop job. User should play a significant role in assessing the computer workstation and environment. The fit between body and workstation is the most crucial in healthy use of computer. I believe that frequent and short rest breaks are always better than less frequent but longer breaks for reducing fatigue at work. I should clear up all the items which I frequently use from the desktop Regular risk assessment can reduce risk of injuries and occupational diseases. I believe that the Display Screen Equipment regulations enacted by the Labour Department are the reason for increasing public’s awareness of healthy computer use. It is essential to attend training sessions on how to correctly modify the workstation in addition to the risk assessments. I believe that task rotation can reduce the stress experienced at the workplace. You should walk away from your work station when taking a rest break. Besides the light from the ceiling, it is preferable for me to install a light close to the monitor. It is important to have little job task variation to minimize the interruption to my work routine. I believe that my compliance to the occupational safety and health guidelines can reduce the risk of injury at the workplace.

footrest [24]. These changes target workers’ discomforts directly, thus reducing their physical and mental discomfort. The DSE RAM System provided the opportunity for the worker participants to take part in the workstation assessment and set preference on the potential modifications for inclusion in the recommendations for the workstation modification. The findings indicated that the participatory processes initiated by the System could lead to behavioural but not attitudinal changes among the participants. There were significant behavioural changes as a result from the use of the DSE RAM System. These behaviours included using taking rest breaks and attending to occupational health information. As revealed by

1.461

95% CI Lower Upper 0.755 2.825

1.391 1.785 0.487 0.695

0.593 0.736 0.184 0.242

3.265 4.328 1.289 1.997

0.556 0.584 0.974

0.178 0.236 0.379

1.743 1.444 2.505

2.191

0.739

6.499

0.541 0.974 0.974 0.649 1.136

0.200 0.345 0.379 0.256 0.421

1.463 2.747 2.505 1.643 3.063

Wahlström [28] and Vink et al. [26], workers tended to prefer making less dramatic changes to their workstation and work task under a normal circumstance. Attending to occupational health information and taking more frequent rest breaks would not require workers to make changes to their workstation. This can explain why these behavioural changes would be more likely to be adopted by the participants [27]. A review of the recommendations generated by the DSE RAM System suggested that the ‘use of footrest’ was the most common recommendations prescribed by the System. There are two observations on this issue. First, the needs for a footrest might be due to the excessively high workstation or users who were not tall and/or did

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W.-Y. Ho et al. / Effectiveness of computerized risk assessment system

not having long legs. Second, footrest has not been a standard provision of ergonomics equipment in the company. As the majority of the participants in this study were female workers, the provision of footrest therefore would be logical. Despite footrest is stipulated as a standard provision in the DSE Regulations in Hong Kong, it is common for companies not to make it available to their workers. It is expected that the provision of footrest would become more common in occupational health practices in the future. The implementation of the DSE RAM System did not seem to bring about significant positive changes in attitudes among the participants toward healthy use of computer. There are two plausible reasons to account for this negative finding: inadequate communication with the workers, and lack of education and skill training on the System. Schulte et al. [39] stressed the importance of communicating the value of ergonomic intervention program to worker participants. They further suggested that the information delivered can be in the form of a campaign, from a creditable source, and appropriate to the workers. Haslam [37], on the other hand, revealed that education and training were the essential elements for leading to long-lasting behavioural changes and continually raise awareness about safety and health within organization. Zeidi et al. [40] further indicated that educational sessions on occupational health were effective for formulating positive beliefs in occupational health. The change in the belief is crucial for bringing about positive changes in attitudes [41,42]. In other words, educational sessions which focuses on formulating positive belief in healthy use of computer at the workplace would enhance positive attitudes leading to behavioural changes among the workers [43,44]. The DSE RAM System does not have educational sessions and a skill training component. The participants in this study were only involved in working with the “assessor” (occupational safety officer) to complete the assessment module, setting preferences for modifications of the workstation, and discussing feasibility of the recommendations on modification. This could be the reason for explaining the implementation of the System did not necessarily leading to a positive attitudinal change in healthy computer use at the workplace.

5. Limitations and implications The design of the study and background of the subjects could confound part of the results of this study.

First, the participants were not blinded from the intervention which they received. This would inevitably generate potential halo effect among the study group which might confound the between-group comparisons. Second, the physical proximity of the participants in the study and control groups could not prevent exchanges on the use of the System and occupational health information. All the participants were recruited from the same department and their workstations were located in the same office area. This would have a negative impact on the effect of the System on the comparison groups. Before the introduction of the System to the corporation, there were a few occupational safety and health programs launched. These programs also covered risk assessments and modifications of workstations. Its effects could have been contaminated by this factor. Future studies should explore the effects of combining educational and skill training sessions together with the DSE RAM System on enhancing healthy ergonomic in workplace. More importantly, the focus can be placed on relating behavioural with attitudinal changes leading to alleviating work-related symptoms. A follow up study could also be possible to elucidate the long-term effect of using the DSE RAM System. Further studies should also investigate the benefits of other features of the System such as standardization of the risk assessment process and on-line monitoring of the results obtained from the risk assessments. It is also recommendable to explore the applicability of this System to other corporations such as in the financial sector in which the efficiency of the workstation system and stressful working environment are the core concerns of the workers’ occupational safety and health.

6. Conclusion Our findings indicate that use of the DSE RAM System is, to a certain extent, effective for enhancing positive behavioural changes towards better occupational health in the workplace, i.e. reduction in physical discomfort and mental fatigue. However, there is no evidence showing that the System was able to bring about positive attitudinal changes. The System involves worker to conduct one’s own risk assessment and participate in the decision making on enhancing a safe workplace. Our findings further support the notion that workers’ participation and integration of ergonomics into the management are important for successful implementation of occupational health

W.-Y. Ho et al. / Effectiveness of computerized risk assessment system

programs. Together with educational and skill training sessions on occupational health at the workplace, the DSE RAM System offers a venue for implementing participatory ergonomics at the workplace.

Acknowledgement The authors would like to thank the Health and Safety Office of The Hong Kong Polytechnic University and HSBC for their assistance in recruiting the participants for this study.

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