Occupational Medicine 2005;55:121-127 doi:10.1093/occmed/kqi029 Musculoskeletal disorders and visual strain in intensive data processing workers Valerie Woods Background This study was conducted for a UK Trade Union in response to increasing numbers of health complaints among intensive computer workers in a data processing environment. Aim To estimate prevalence of musculoskeletal pain/discomfort and visual strain symptoms among data processing workers and to explore associations with work factors. Methods A self-report questionnaire was distributed to data processors (n=175)and a control group (n=129) in the same organization Results Eighty-six per cent of data processors reported musculoskeletal pain/discomfort in the previous year, with the highest prevalence rate found for the neck(58%).The 12 month reported prevalence for visual strain symptoms was 47%,tired eyes (41%)was the most commonly reported symptom.In the last week,56%reported pain/discomfort and 25%visual strain symptoms.Data processors reporting pain in the previous year were more likely to be dissatisfied with their jobs(P<0.01),to report a lack of choice in deciding what they did at work (P<0.02),to have insufficient time to complete work (P<0.05)or to receive help from others when time was limited (P<0.03). Conclusion The prevalence of self-reported musculoskeletal pain/discomfort and visual strain symptoms was high among data processors.A systematic approach to risk reduction addressing organizational, psychosocial and physical work factors is required.This study has implications for reorganization of this and other intensive computer work,given the increasing requirement for intensive computing work in many industrial sectors.More research is needed to investigate interactions between job demands and support systems for these workers. Key words Data processing;musculoskeletal pain/discomfort;performance targets;sedentary work;vigilance; visual strain. Introduction overuse [16]have been identified as MSD risk factors.A relationship between upper extremity pain and duration Musculoskeletal pain and visual discomfort are the main of keyboard use has also been documented [17,18].In health problems reported by computer workers [1,2]and addition relationships exist between psychosocial factors the major contributors to workdays lost [3].Prevalence of (e.g.social support from colleagues/supervisors)and musculoskeletal disorders among keyboards users has musculoskeletal pain [17,19-23].For example,high job been reported to be as high as 81%[4].Similarly,86% demands,time pressure and more than 15 h keyboarding female and 68%male call centre staff reported muscu- per week were identified as risk factors for forearm pain loskeletal pain with the neck and shoulder regions most [24]. frequently affected [5]. Although relatively few studies have investigated visual Physical workplace factors (e.g.prolonged static strain,it has been linked to musculoskeletal complaints muscle load,workstation factors)have been identified as risk factors for musculoskeletal diseases (MSD) [3,25]and work stress [25].Psychosocial and organis- [6-11].In the computing environment,incorrect com- ational factors were related to the experiences of puter workstation set-up [12],prolonged work in fixed or psychological stress,musculoskeletal disorders and pro- awkward positions [13-15],seated and static work,and blems with vision among computer users [26].One study found that a high incidence of neck,wrist and back Robens Centre for Health Ergonomics,University of Surrey,Guildford complaints,headaches and eyestrain stemmed from GU2 7TE,UK. exceptionally long periods of sitting with the neck flexed Correspondence to:Valerie Woods,Robens Centre for Health Ergonomics, University of Surrey,Guildford GU2 7TE,UK.Tel:+1483 686738; while 'number crunching'from spread sheets on the fax:+1483 689395;e-mail:v.woods @surrey.ac.uk computer screen in a finance auditing job [27].A large Occupational Medicine,Vol.55 No.2 Society of Occupational Medicine20;all rights reserved 121
Musculoskeletal disorders and visual strain in intensive data processing workers Valerie Woods ............................................................................................................................... ............................. Background This study was conducted for a UK Trade Union in response to increasing numbers of health complaints among intensive computer workers in a data processing environment. ............................................................................................................................... ............................. Aim To estimate prevalence of musculoskeletal pain/discomfort and visual strain symptoms among data processing workers and to explore associations with work factors. ............................................................................................................................... ............................. Methods A self-report questionnaire was distributed to data processors (n ¼ 175) and a control group (n ¼ 129) in the same organization. ............................................................................................................................... ............................. Results Eighty-six per cent of data processors reported musculoskeletal pain/discomfort in the previous year, with the highest prevalence rate found for the neck (58%). The 12 month reported prevalence for visual strain symptoms was 47%, tired eyes (41%) was the most commonly reported symptom. In the last week, 56% reported pain/discomfort and 25% visual strain symptoms. Data processors reporting pain in the previous year were more likely to be dissatisfied with their jobs (P , 0.01), to report a lack of choice in deciding what they did at work (P , 0.02), to have insufficient time to complete work (P , 0.05) or to receive help from others when time was limited (P , 0.03). ............................................................................................................................... ............................. Conclusion The prevalence of self-reported musculoskeletal pain/discomfort and visual strain symptoms was high among data processors. A systematic approach to risk reduction addressing organizational, psychosocial and physical work factors is required. This study has implications for reorganization of this and other intensive computer work, given the increasing requirement for intensive computing work in many industrial sectors. More research is needed to investigate interactions between job demands and support systems for these workers. ............................................................................................................................... ............................. Key words Data processing; musculoskeletal pain/discomfort; performance targets; sedentary work; vigilance; visual strain. ............................................................................................................................... ............................. Introduction Musculoskeletal pain and visual discomfort are the main health problems reported by computer workers [1,2] and the major contributors to workdays lost [3]. Prevalence of musculoskeletal disorders among keyboards users has been reported to be as high as 81% [4]. Similarly, 86% female and 68% male call centre staff reported musculoskeletal pain with the neck and shoulder regions most frequently affected [5]. Physical workplace factors (e.g. prolonged static muscle load, workstation factors) have been identified as risk factors for musculoskeletal diseases (MSD) [6–11]. In the computing environment, incorrect computer workstation set-up [12], prolonged work in fixed or awkward positions [13–15], seated and static work, and overuse [16] have been identified as MSD risk factors. A relationship between upper extremity pain and duration of keyboard use has also been documented [17,18]. In addition relationships exist between psychosocial factors (e.g. social support from colleagues/supervisors) and musculoskeletal pain [17,19–23]. For example, high job demands, time pressure and more than 15 h keyboarding per week were identified as risk factors for forearm pain [24]. Although relatively few studies have investigated visual strain, it has been linked to musculoskeletal complaints [3,25] and work stress [25]. Psychosocial and organisational factors were related to the experiences of psychological stress, musculoskeletal disorders and problems with vision among computer users [26]. One study found that a high incidence of neck, wrist and back complaints, headaches and eyestrain stemmed from exceptionally long periods of sitting with the neck flexed while ‘number crunching’ from spread sheets on the computer screen in a finance auditing job [27]. A large Occupational Medicine 2005;55:121–127 doi:10.1093/occmed/kqi029 Occupational Medicine, Vol. 55 No. 2 q Society of Occupational Medicine 2005; all rights reserved 121 Correspondence to: Valerie Woods, Robens Centre for Health Ergonomics, University of Surrey, Guildford GU2 7TE, UK. Tel: þ1483 686738; fax: þ1483 689395; e-mail: v.woods@surrey.ac.uk Robens Centre for Health Ergonomics, University of Surrey, Guildford GU2 7TE, UK
122 OCCUPATIONAL MEDICINE percentage of data processing workers reported chronic The researchers made a preliminary visit to a data physical complaints(i.e.eyestrain,musculoskeletal pains, processing centre to observe the work environment and headaches)and emotional stress that they believed were tasks performed to inform the questionnaire design.An work related [28]. anonymous retrospective epidemiological questionnaire This study was conducted for a trade union in the UK comprised questions on age,gender,hours worked; that had received an increasing number of complaints of annual/7 day prevalence of pain/discomfort and visual aches,pains and visual strain from intensive computer strain symptoms;and work organisation and work workers in data processing environments.The aims of this activities.The presence of musculoskeletal pain and study were to (i)estimate the prevalence of musculoske- discomfort was investigated using the Nordic Musculo- letal pain/discomfort and visual strain symptoms among skeletal Questionnaire [29].Visual strain symptoms were data processors at two sites and(ii)explore the association considered to be impaired visual performance,head- with work factors (e.g.work pace and intensity)and aches,tired,red and sore eyes,as outlined in the Display satisfaction (e.g.social support received).A participatory Screen Equipment Regulations [30].Items on hours per approach was undertaken;workers'views were used in day spent on various tasks,perceived work speed and combination with expert assessments to meet the study intensity,availability of help and support,decision aims,however only the questionnaire results comparing making regarding work and breaks were used in previous data processors and a control group are reported here. studies [31,32]. Two data processing centres,deemed representative of the 36 sites in the organisation,were selected by the trade Methods union for in-depth study.Both sites were located in large cities;159 data processors worked at one site and 86 at The study was conducted in a large national organisation the other.Questionnaires were completed in work time in the distribution sector.The work of the intensive and collected by the researchers after a Union represen- computer data processing workforce was office based, tative explained the study to all data processing and sedentary,visually intensive and required a high level of manual workers at work when the researchers visited the vigilance.The worker sat at a purpose built computer sites to conduct assessments.All data processors at work workstation,focused on information that appeared on the that day completed the survey (n=175)representing display screen and entered missing data or corrected 71%of all data processors at the two sites (n=245). existing information.The presentation of information Questionnaires were distributed to the same number of was continuous and workers made quick decisions to controls (n=245)and completed by 53%(n=129). meet performance targets;a wall display indicated rates The data were analysed using SPSS version 11.0.0 of information processed throughout 9h shifts.Data [33].Independent t-tests were conducted on the back- processors were expected to make 10 000 keystrokes per ground variables to investigate differences between work hour.The data processing job existed because a machine groups.Pearson Chi-squares were calculated to identify could not meet task demands:workers inputted and differences between groups with respect to prevalence of corrected information that the machine could not self-reported health problems and associations between recognize.Breaks were fixed with one 10min break potential risk factors and reported health problems.In away from the workstation after 60 min work;in addition order to investigate the relationship between the job type two short breaks and a lunch break were taken.The work and the presence of musculoskeletal or visual strain was sometimes interspersed with manual sorting work, symptoms,odds ratios (OR)and their 95%confidence depending on workload elsewhere in the organization. intervals (95%CD)were calculated.ORs were used as Overtime work (both data processing and manual)was estimates of the relative risks.Only significant ORs are undertaken frequently,often following a regular presented. workshift. In order to place the health problems of the data processors in the organizational context,data were also Results collected from other workers at the same sites.These manual workers stood or sat to sort items of varying The data processing (82%)and control (75%)samples weights for long periods (over 8 h per day)in a large open comprised a high proportion of male workers.The plan room.The sorting work required continual move- groups did not differ significantly with respect to age, ment of the upper limbs and bending/twisting to lift and hours worked per day or years in this type of work, move items.It also comprised a visual component as however data processors worked significantly more hours information on items was read before sorting.Some of per week than the controls (Table 1).Seventy-one per these workers also operated machinery.The workers cent (n=123)of data processors conducted some conducted regular overtime manual work. overtime manual work (mode =4h,range 1-9);11%
percentage of data processing workers reported chronic physical complaints (i.e. eyestrain, musculoskeletal pains, headaches) and emotional stress that they believed were work related [28]. This study was conducted for a trade union in the UK that had received an increasing number of complaints of aches, pains and visual strain from intensive computer workers in data processing environments. The aims of this study were to (i) estimate the prevalence of musculoskeletal pain/discomfort and visual strain symptoms among data processors at two sites and (ii) explore the association with work factors (e.g. work pace and intensity) and satisfaction (e.g. social support received). A participatory approach was undertaken; workers’ views were used in combination with expert assessments to meet the study aims, however only the questionnaire results comparing data processors and a control group are reported here. Methods The study was conducted in a large national organisation in the distribution sector. The work of the intensive computer data processing workforce was office based, sedentary, visually intensive and required a high level of vigilance. The worker sat at a purpose built computer workstation, focused on information that appeared on the display screen and entered missing data or corrected existing information. The presentation of information was continuous and workers made quick decisions to meet performance targets; a wall display indicated rates of information processed throughout 9 h shifts. Data processors were expected to make 10 000 keystrokes per hour. The data processing job existed because a machine could not meet task demands: workers inputted and corrected information that the machine could not recognize. Breaks were fixed with one 10 min break away from the workstation after 60 min work; in addition two short breaks and a lunch break were taken. The work was sometimes interspersed with manual sorting work, depending on workload elsewhere in the organization. Overtime work (both data processing and manual) was undertaken frequently, often following a regular workshift. In order to place the health problems of the data processors in the organizational context, data were also collected from other workers at the same sites. These manual workers stood or sat to sort items of varying weights for long periods (over 8 h per day) in a large open plan room. The sorting work required continual movement of the upper limbs and bending/twisting to lift and move items. It also comprised a visual component as information on items was read before sorting. Some of these workers also operated machinery. The workers conducted regular overtime manual work. The researchers made a preliminary visit to a data processing centre to observe the work environment and tasks performed to inform the questionnaire design. An anonymous retrospective epidemiological questionnaire comprised questions on age, gender, hours worked; annual/7 day prevalence of pain/discomfort and visual strain symptoms; and work organisation and work activities. The presence of musculoskeletal pain and discomfort was investigated using the Nordic Musculoskeletal Questionnaire [29]. Visual strain symptoms were considered to be impaired visual performance, headaches, tired, red and sore eyes, as outlined in the Display Screen Equipment Regulations [30]. Items on hours per day spent on various tasks, perceived work speed and intensity, availability of help and support, decision making regarding work and breaks were used in previous studies [31,32]. Two data processing centres, deemed representative of the 36 sites in the organisation, were selected by the trade union for in-depth study. Both sites were located in large cities; 159 data processors worked at one site and 86 at the other. Questionnaires were completed in work time and collected by the researchers after a Union representative explained the study to all data processing and manual workers at work when the researchers visited the sites to conduct assessments. All data processors at work that day completed the survey (n ¼ 175) representing 71% of all data processors at the two sites (n ¼ 245). Questionnaires were distributed to the same number of controls (n ¼ 245) and completed by 53% (n ¼ 129). The data were analysed using SPSS version 11.0.0 [33]. Independent t-tests were conducted on the background variables to investigate differences between work groups. Pearson Chi-squares were calculated to identify differences between groups with respect to prevalence of self-reported health problems and associations between potential risk factors and reported health problems. In order to investigate the relationship between the job type and the presence of musculoskeletal or visual strain symptoms, odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated. ORs were used as estimates of the relative risks. Only significant ORs are presented. Results The data processing (82%) and control (75%) samples comprised a high proportion of male workers. The groups did not differ significantly with respect to age, hours worked per day or years in this type of work, however data processors worked significantly more hours per week than the controls (Table 1). Seventy-one per cent (n ¼ 123) of data processors conducted some overtime manual work (mode ¼ 4 h, range 1–9); 11% 122 OCCUPATIONAL MEDICINE
V.WOODS:MUSCULOSKELETAL DISORDERS AND VISUAL STRAIN IN DATA PROCESSING WORKERS 123 Table 1.Age of the respondents and hours and years worked Table 3.The odds ratios (OR)with 95%confidence intervals (95%CI)for pain/discomfort in the different regions reported by Data Controls Significance data processors in the previous year/7 days in comparison with the processors (n=129) control group (n=175) Last year pain, Last 7 days pain, Mean SD Mean SD OR (95%CI) OR (95%CI) Age(years) 35.5 7.1 38.6 10.3 ns Neck 2.9(1.8-4.7) 2.8(1.5-5.3) Hours per day 9.1 2.1 8.6 2.7 ns Lower back 1.6(1.0-2.5) ns Hours per week 47.9 11.2 43.9 11.6 P Left elbow 9 25 3 ns Right elbow > ns 2 ns Hips/thighs 7 12 3 <0.0001, <0.001."P<0.01,P<0.05,ns not significant
(n ¼ 14) of controls conducted some overtime data processing (mode ¼ 4 h, range 2–9). Eighty-six per cent of data processing workers reported musculoskeletal pain and discomfort in the previous year and 56% reported these problems in the last week. Seventy-three per cent of controls reported musculoskeletal problems in the last year and 42% in the last week. Data processors were twice as likely to report pain/discomfort in the last year (OR ¼ 2.3, 95% CI ¼ 1.31–4.18) and somewhat more likely to report problems in the last 7 days (OR ¼ 1.8, 95% CI ¼ 1.16– 2.8) than the controls. The main body areas of concern for data processors were the neck, lower and upper back, wrists/hands and shoulders. The main areas of concern for controls were the lower back, neck and ankles/feet. Data processors were significantly more likely to report neck, lower and upper back, wrists/hands, shoulders and left elbow pain/discomfort than controls; controls were more likely to report ankle/feet pain and discomfort (Tables 2 and 3). The health outcomes for the two groups of workers did not differ; pain and discomfort had lead to approximately 14% of data processors and controls being absent from work in the last year and 30% seeking medical advice. Eighty-one per cent of data processing staff attributed their pain and discomfort to work, citing poor seating (49%), constant keying (24%), sitting in the same position for hours (23%) and computer set-up (12%) as possible causes. Sixty-seven per cent of controls attributed pain and discomfort to work, reporting standing most of the day (20%), lifting and bending (19%), continual movement of wrists/shoulders (18%) and poor seating (16%) as possible causes. Forty-seven per cent of data processors reported at least one visual strain symptom in the last year; 9% reported all four symptoms. Twenty-three per cent of controls reported at least one visual strain symptom in the last year while 2% reported all four symptoms. Twenty- five per cent of data processors and 9% of controls reported at least one visual strain symptom during the previous week. Data processors were three times more likely to report visual strain symptoms in the last year (OR ¼ 2.9, 95% CI ¼ 1.76–4.81) and in the last week Table 1. Age of the respondents and hours and years worked Data processors (n ¼ 175) Controls (n ¼ 129) Significance Mean SD Mean SD Age (years) 35.5 7.1 38.6 10.3 ns Hours per day 9.1 2.1 8.6 2.7 ns Hours per week 47.9 11.2 43.9 11.6 P , 0.003 Years worked 6.5 3.6 10.6 6.6 ns Table 3. The odds ratios (OR) with 95% confidence intervals (95% CI) for pain/discomfort in the different regions reported by data processors in the previous year/7 days in comparison with the control group Last year pain, OR (95% CI) Last 7 days pain, OR (95% CI) Neck 2.9 (1.8–4.7) 2.8 (1.5–5.3) Lower back 1.6 (1.0–2.5) ns Right wrist/hand 7.7 (4.2–13.9) 3.5 (1.7–7.4) Left wrist/hand 5.3 (3.0–9.2) 4.2 (1.9–9.3) Right shoulder 1.9 (1.2–3.0) 2.5 (1.3–5.1) Left shoulder 2.7 (1.5–4.7) 4.9 (2.0–12.2) Upper back ns 2.2 (1.1–4.6) Left elbow 4.2 (1.2–14.8) ns Ankles/feet 0.3 (0.2–0.6) 0.41 (0.2–0.9) Table 2. Prevalence (%) of pain/discomfort reported by 175 data processors (Data P.) and 129 controls in previous year/week % Last year % Last 7 days Data P. Controls Significance Data P. Controls Significance Neck 58 33 pppp 27 12 ppp Lower back 54 43 p 25 23 ns Right wrist/hand 52 12 pppp 23 8 pppp Left wrist/hand 49 16 pppp 22 6 pppp Right shoulder 39 26 pp 21 9 pp Left shoulder 34 16 pppp 19 5 pppp Upper back 30 20 p 17 9 p Knees 14 12 ns 4 6 ns Ankles/feet 14 33 pppp 7 16 pp Left elbow 9 2 pp 3 1 ns Right elbow 7 5 ns 2 1 ns Hips/thighs 7 12 ns 3 8 p ppppP , 0:0001; pppP , 0:001; ppP , 0:01; pP , 0:05; ns ¼ not significant. V. WOODS: MUSCULOSKELETAL DISORDERS AND VISUAL STRAIN IN DATA PROCESSING WORKERS 123
124 OCCUPATIONAL MEDICINE Table 4.Prevalence(%)of visual strain symptoms reported by 175 data processors (Data P.)and 129 controls in previous year/7 days Last year Last 7 days Data P. Controls Significance Data P. Controls Significance Tired eyes 41 21 26 12 Headaches 30 13 12 Impaired visual performance 11 15 Red or sore eyes 26 14 16 All symptoms 9 4 *P<0.0001,*p<0.001.p<0.01.*P <0.05,ns not significant. Table 5.The odds ratios (OR)with 95%confidence intervals more job dissatisfaction than the control group but no (95%CI)for visual strain symptoms reported by data processors in differences were evident for social support (Table 6). the previous year/7 days in comparison with the control group The majority of data processors reported that they had to work fast and intensively.Low levels of job control (i.e. Visual strain symptom Last year Last 7 days pain,OR pain,OR how and when they did their work,when they could take (95%CD (95%CD breaks)were also reported.Nearly half the data processors reported that they did not get help if time Tired eyes 2.6(1.6-4.4) 2.4(1.3-4.6) was limited.Overall,the control group reported signifi- Headaches 2.8(1.5-5.1) 3.4(1.2-9.3) cantly less dissatisfaction with most of these work Impaired visual performance 3.0(1.6-5.8) 7.7(2.3-25.9 organizational aspects than the data processors(Table 7). Red or sore eyes 2.5(1.4-4.7) 4.7(1.8-12.6) In contrast to those without pain,data processors who reported pain in the last year were more likely to be dissatisfied with their jobs (P<0.01),to report a lack of (OR 3.5,95%CI 1.72-7.09)than controls.Data choice in deciding what they did at work (P<0.02),to processors were significantly more likely to report each find they did not have enough time to do their work visual strain symptom than controls (Tables 4 and 5). (P<0.05)and to state that help was not available if time Forty-six per cent of data processors believed their was limited (P<0.03).The controls who reported pain symptoms were work related.Looking at the computer for a long time (26%),poor screen quality (14%)and poor environmental conditions (11%)were reported as Table 7.Percentage of workers who reported frequently experien- possible causes.Twenty-four per cent of controls believed cing work organization problems these problems were work related,citing inadequate Significance lighting (10%),concentration required to read(9%)and Data Controls processors poor environmental conditions(8%)as possible causes. Over 1/3 of data processors reported being dissatisfied Never had a choice in 81 67 with their jobs and with support received from super- deciding what they visors;1/5 reported being dissatisfied with support did at work received from colleagues.The data processors reported Could never decide 78 68 when to take breaks Table 6.Percentage of workers who were dissatisfied or very Never had a choice in 69 dissatisfied with aspects of their job how they did their work Often required to work 65 46 very intensively Data Controls Significance Often required to work 61 processors very fast Never got help if not 43 Dissatisfied with job 35 19 enough time Dissatisfied with help/ 37 29 ns Never had enough time 21 16 ns support from supervisors to do all work Dissatisfied with help/ 21 18 ns Often difficulty reaching 5 14 ns support from colleagues targets "p<0.0001,p<0.001,“P<0.01,P<0.05,ns=not p<0.0001,“P<0.001,“P<0.01,P<0.05,ns=not significant. significant
(OR ¼ 3.5, 95% CI ¼ 1.72–7.09) than controls. Data processors were significantly more likely to report each visual strain symptom than controls (Tables 4 and 5). Forty-six per cent of data processors believed their symptoms were work related. Looking at the computer for a long time (26%), poor screen quality (14%) and poor environmental conditions (11%) were reported as possible causes. Twenty-four per cent of controls believed these problems were work related, citing inadequate lighting (10%), concentration required to read (9%) and poor environmental conditions (8%) as possible causes. Over 1/3 of data processors reported being dissatisfied with their jobs and with support received from supervisors; 1/5 reported being dissatisfied with support received from colleagues. The data processors reported more job dissatisfaction than the control group but no differences were evident for social support (Table 6). The majority of data processors reported that they had to work fast and intensively. Low levels of job control (i.e. how and when they did their work, when they could take breaks) were also reported. Nearly half the data processors reported that they did not get help if time was limited. Overall, the control group reported signifi- cantly less dissatisfaction with most of these work organizational aspects than the data processors (Table 7). In contrast to those without pain, data processors who reported pain in the last year were more likely to be dissatisfied with their jobs (P , 0.01), to report a lack of choice in deciding what they did at work (P , 0.02), to find they did not have enough time to do their work (P , 0.05) and to state that help was not available if time was limited (P , 0.03). The controls who reported pain Table 4. Prevalence (%) of visual strain symptoms reported by 175 data processors (Data P.) and 129 controls in previous year/7 days % Last year % Last 7 days Data P. Controls Significance Data P. Controls Significance Tired eyes 41 21 pppp 26 12 p Headaches 30 13 ppp 12 4 pp Impaired visual performance 27 11 ppp 15 2 pppp Red or sore eyes 26 14 pp 16 4 ppp All symptoms 9 2 4 0 ppppP , 0.0001, pppP , 0:001; ppP , 0:01; pP , 0:05; ns ¼ not significant. Table 5. The odds ratios (OR) with 95% confidence intervals (95% CI) for visual strain symptoms reported by data processors in the previous year/7 days in comparison with the control group Visual strain symptom Last year Last 7 days pain, OR (95% CI) pain, OR (95% CI) Tired eyes 2.6 (1.6–4.4) 2.4 (1.3–4.6) Headaches 2.8 (1.5–5.1) 3.4 (1.2–9.3) Impaired visual performance 3.0 (1.6–5.8) 7.7 (2.3–25.9) Red or sore eyes 2.5 (1.4–4.7) 4.7 (1.8–12.6) Table 6. Percentage of workers who were dissatisfied or very dissatisfied with aspects of their job Data processors Controls Significance Dissatisfied with job 35 19 pp Dissatisfied with help/ support from supervisors 37 29 ns Dissatisfied with help/ support from colleagues 21 18 ns ppppP , 0:0001; pppP , 0:001; ppP , 0:01; pP , 0:05; ns ¼ not significant. Table 7. Percentage of workers who reported frequently experiencing work organization problems Data processors Controls Significance Never had a choice in deciding what they did at work 81 67 p Could never decide when to take breaks 78 68 pp Never had a choice in how they did their work 69 48 pp Often required to work very intensively 65 46 pp Often required to work very fast 61 46 p Never got help if not enough time 43 9 pppp Never had enough time to do all work 21 16 ns Often difficulty reaching targets 15 14 ns ppppP , 0:0001; pppP , 0:001; ppP , 0:01; pP , 0:05; ns ¼ not significant. 124 OCCUPATIONAL MEDICINE
V.WOODS:MUSCULOSKELETAL DISORDERS AND VISUAL STRAIN IN DATA PROCESSING WORKERS 125 in the last year were more likely to report:a lack of choice programme should be participatory in approach and in deciding what they did (P<0.02)or how they did involve all interested parties,i.e.employers,managers, their work(P<0.001),not being able to decide when to supervisors,trainers,equipment and furniture suppli- take breaks (P<0.007),having to work fast (P<0.05) ers/manufacturers and the workforce and finding they did not have enough time to do their This study has implications for reorganization of this work(P<0.06),than controls who did not report pain. and other intensive computer work.Since the numbers of The controls who reported pain in the last week were workers using computers are increasing,injuries and ill- more likely to report being dissatisfied with their jobs health related to computers may also be expected to (P<0.04),having to work intensively (P<0.03)and increase if actions are not taken [3 with resultant costs. often having difficulty reaching targets(P<0.03).There Given the increase in the number of intensive computer were no significant associations between those who workers whose main task is to focus on a computer screen reported eye problems in the previous year/week and to provide,access or input information in many industrial these work organisational issues for either work group. sectors (e.g.call centre workers),it is important that these data are reported as national targets have been set for the reduction of occupational ill-health and injury in Great Discussion Britain.In order to act on these health problems,it is important for policy makes,practitioners and employers A high prevalence of pain/discomfort was reported by to recognise the research evidence that changing physical data processors in this study.This corresponded with factors alone will not necessarily alleviate problems findings from other studies on data processing [34]and [19-23]in this or other types of work;environmental, computer work [4,5,25].The most frequently reported organisational,individual and psychosocial factors area of concern was the neck,which was similar to should also be addressed.Issues of low control (whether findings from Toomingas et al.[5].Comparison with over the environment or the task)along with poor Health and Safety Executive (HSE)data for male communication with regard to work matters,inadequate workers indicated that reported neck,shoulders,wrists/ social support from co-workers and supervisors/man- hands and back problems were of particular concern agers (e.g.for healthy working practises,support when compared with national data(e.g.58%neck pain among pressure is high)and lack of consultation (e.g.for new data processors,30%in the HSE sample)[35].The equipment,software changes,shift pattern changes)are number seeking medical advice for aches and pains was important to take into consideration.This approach is in high(30%)when compared with other workers [36].The line with Moray's [37]model of ergonomics,which prevalence of self-reported visual strain symptoms among stresses the contribution of individual behaviour,physical data processors was similar to findings of a small number ergonomics,team and group behaviour,organizational of other studies on computer users [27,28]. and management behaviour,legal and regulatory rules, Workers'reports of possible causes of these problems and societal and cultural pressures for safe work systems. were similar to those identified in previous research Further study of the data processors following the [12-161.The factors identified by data processors were implementation of changes using a participative mainly physical work factors(e.g.poor seating),although approach would help clarify the effectiveness of various job design issues were reported(e.g.the requirement to types of interventions for reducing the health problems in sit in the same position for many hours to conduct the this type of work.More research is needed to investigate task).In addition,statistical analysis indicated that data the interaction between the job demands and the support processors reporting pain in the last year were more likely systems for these workers. to report problems with respect to job dissatisfaction,lack The applied nature of this investigation designed to of control over work,time pressures and low social meet client demands has led to weaknesses in the study support.These psychosocial and organisational factors design,and these are recognised as potential sources of were also found to be related to experiences of MSD and bias,e.g.the trade union chose the data processing visual strain in other studies [19-23,26].No associations centres and these sites represented only 2 of 36 were found with overall reports of visual strain symptoms organisational sites;the data processing centres differed and work factors in this study,however analysis of in terms of space allocation,workstation set-ups and individual symptoms (e.g.red eyes)revealed significant environmental factors;the trade union representative findings,but the sample numbers were too small to may have introduced feelings of pressure to complete the report. questionnaire.In addition,the manual workers were not The study findings suggest that a systematic approach an ideal control group as the nature of their work differed, to risk reduction in this workforce is required,which requiring different physical loads and other exposures addresses organisational,psychosocial and physical work (e.g.different pain and discomfort patterns were factors at the workplace.Ideally,the risk reduction not unlikely given the nature of their work).In addition
in the last year were more likely to report: a lack of choice in deciding what they did (P , 0.02) or how they did their work (P , 0.001), not being able to decide when to take breaks (P , 0.007), having to work fast (P , 0.05) and finding they did not have enough time to do their work (P , 0.06), than controls who did not report pain. The controls who reported pain in the last week were more likely to report being dissatisfied with their jobs (P , 0.04), having to work intensively (P , 0.03) and often having difficulty reaching targets (P , 0.03). There were no significant associations between those who reported eye problems in the previous year/week and these work organisational issues for either work group. Discussion A high prevalence of pain/discomfort was reported by data processors in this study. This corresponded with findings from other studies on data processing [34] and computer work [4,5,25]. The most frequently reported area of concern was the neck, which was similar to findings from Toomingas et al. [5]. Comparison with Health and Safety Executive (HSE) data for male workers indicated that reported neck, shoulders, wrists/ hands and back problems were of particular concern compared with national data (e.g. 58% neck pain among data processors, 30% in the HSE sample) [35]. The number seeking medical advice for aches and pains was high (30%) when compared with other workers [36]. The prevalence of self-reported visual strain symptoms among data processors was similar to findings of a small number of other studies on computer users [27,28]. Workers’ reports of possible causes of these problems were similar to those identified in previous research [12–16]. The factors identified by data processors were mainly physical work factors (e.g. poor seating), although job design issues were reported (e.g. the requirement to sit in the same position for many hours to conduct the task). In addition, statistical analysis indicated that data processors reporting pain in the last year were more likely to report problems with respect to job dissatisfaction, lack of control over work, time pressures and low social support. These psychosocial and organisational factors were also found to be related to experiences of MSD and visual strain in other studies [19–23,26]. No associations were found with overall reports of visual strain symptoms and work factors in this study, however analysis of individual symptoms (e.g. red eyes) revealed significant findings, but the sample numbers were too small to report. The study findings suggest that a systematic approach to risk reduction in this workforce is required, which addresses organisational, psychosocial and physical work factors at the workplace. Ideally, the risk reduction programme should be participatory in approach and involve all interested parties, i.e. employers, managers, supervisors, trainers, equipment and furniture suppliers/manufacturers and the workforce. This study has implications for reorganization of this and other intensive computer work. Since the numbers of workers using computers are increasing, injuries and illhealth related to computers may also be expected to increase if actions are not taken [3] with resultant costs. Given the increase in the number of intensive computer workers whose main task is to focus on a computer screen to provide, access or input information in many industrial sectors (e.g. call centre workers), it is important that these data are reported as national targets have been set for the reduction of occupational ill-health and injury in Great Britain. In order to act on these health problems, it is important for policy makes, practitioners and employers to recognise the research evidence that changing physical factors alone will not necessarily alleviate problems [19–23] in this or other types of work; environmental, organisational, individual and psychosocial factors should also be addressed. Issues of low control (whether over the environment or the task) along with poor communication with regard to work matters, inadequate social support from co-workers and supervisors/managers (e.g. for healthy working practises, support when pressure is high) and lack of consultation (e.g. for new equipment, software changes, shift pattern changes) are important to take into consideration. This approach is in line with Moray’s [37] model of ergonomics, which stresses the contribution of individual behaviour, physical ergonomics, team and group behaviour, organizational and management behaviour, legal and regulatory rules, and societal and cultural pressures for safe work systems. Further study of the data processors following the implementation of changes using a participative approach would help clarify the effectiveness of various types of interventions for reducing the health problems in this type of work. More research is needed to investigate the interaction between the job demands and the support systems for these workers. The applied nature of this investigation designed to meet client demands has led to weaknesses in the study design, and these are recognised as potential sources of bias, e.g. the trade union chose the data processing centres and these sites represented only 2 of 36 organisational sites; the data processing centres differed in terms of space allocation, workstation set-ups and environmental factors; the trade union representative may have introduced feelings of pressure to complete the questionnaire. In addition, the manual workers were not an ideal control group as the nature of their work differed, requiring different physical loads and other exposures (e.g. different pain and discomfort patterns were not unlikely given the nature of their work). In addition, V. WOODS: MUSCULOSKELETAL DISORDERS AND VISUAL STRAIN IN DATA PROCESSING WORKERS 125
126 OCCUPATIONAL MEDICINE the limitations of cross-sectional studies are recognised 7.Torp S,Riise T,Moen BE.The impact of psychosocial [38],e.g.inaccurate recall of information,limited work factors on musculoskeletal pain:a prospective study. possibility of determining causal relationships between 70EM2001;43:120-126. the work factors and the musculoskeletal disorders. 8.National Academy of Science.Musculoskeletal Disorders and However,self-report measures of upper extremity and the Workplace:Low Back and Upper Extremities.Washington (DC):National Academy Press,2001. ergonomic exposures have been recognised as potentially 9.Buckle P,Devereux J.The nature of work-related neck and useful in occupational health surveillance programmes upper limb musculoskeletal disorders.Appl Ergon 2002;33: for office work environments [39].In addition,the 207-217. questionnaire response rate was relatively high and was 10.National Institute of Occupational Safety and Health. considered to be a good representation of data processors Musculoskeletal Disorders and Workplace Factors:a Critical in this work environment.Few studies have reported Review of Epidemiological Evidence for Work-Related Muscu- visual strain symptom prevalence and this is important loskeletal Disorders of the Neck,Upper Extremity and Low given the visual intensity of this and other computer Back.Cincinnatti (OH):NIOSH,1997. work.This study has added to the body of research that 11.Hales TR,Bernard BP.Epidemiology of work-related musculoskeletal disorders.Orthop Clin N Am 1996;27: emphasises the role of both physical and psychosocial 679-709. factors in the experience of good health at work.The 12.Sillanpaa J,Huikko S,Nyberg M,et al.Effect of work with findings indicate the need for resources to be directed visual display units on musculoskeletal disorders in the toward exploring effective means of modifying the office environment.Occup Med (Lond)2003;53:443-451. organisation of data processing and other intensive 13.Yu ITS,Wong TW.Musculoskeletal problems among VDU work as well as improving physical and environmental workers in a Hong Kong bank.Occup Med (Lond)1996;46: factors 275-280. 14.Toivonen R,Takala EP.Assessment of the dose-response relationship between VDU work and discomfort.In: Acknowledgements Bullinger HJ,Ziegler J,eds.Human-Computer Interaction: Ergonomics and User Interfaces.New Jersey:Lawrence The author wishes to acknowledge the assistance provided by Erlbaum Associates,1999;27-30. Geoffrey David at the Robens Centre for Health Ergonomics for 15.Straker L,Mekhora K.An evaluation of Visual Display his help in the collection of data for this study. Unit placement by electromyography,posture,discomfort and preference.Int Ind Ergon 2000;26:389-398. 16. Carter JB,Banister EW.Musculoskeletal problems in VDT work:a review.Ergonomics 1994;37:1623-1648 References 17.Smith M,Carayon P.Work organisation,stress and cumulative truama disorders.In:Moon SD,Sauter SL, 1.Aaras A,Horgen G,Ro O.Work with the Visual Display eds.Beyond Biomechanics.Psychological Aspects of Muscu- Unit:health consequences.Int Hum-Comput Int 2000;12: loskeletal Disorders in Office Work.London:Taylor Francis, 107-134. 1996;23-42 2.Balci R,Aghazadeh F,Waly SM.Work-rest schedules for 18.Punnett L,Bergqvist U,et al.Visual Display Unit Work and data entry operators.In:Kumar S,ed.Advances in Upper Extremity Musculoskeletal Disorders:A Review of Occupational Ergonomics and Safety 2.Amsterdam:IOS Epidemiological Findings.Solna,Sweden:National Institute Press,1998;155-158. for Working Life,Arbete och Halsa,16pp.1997. 3.Abib AH,Dutta SP.Epidemiological investigation of 19.Burdorf A,Sorock G.Positive and negative evidence of risk workdays lost due to VDT related injuries.Occup Ergon factors for back disorders.Scand y Work Environ Health 1998;1:285-290. 1997:23:243-256. 4.Kamwendo K,Linton SJ,Moritz U.Neck and shoulder 20.Bongers PM,de Winter CR,Kompier MA,Hildebrandt disorders in medical secretaries.Scand f Rehabil Med 1991; VH.Psychosocial factors at work and musculoskeletal 23:127-133. disease.Scand Y Work Environ Health 1993;19:297-312. 5.Toomingas A,Nilsson T,Hagberg M,Norman K, 21.Acheson D.The Independent Inquiry into Inequalities in Tornqvist EW.Symptoms and clinical findings from the Health Report.London:The Stationary Office,1998. musculoskeletal system among operators at a call center in 22.Macfarlane GJ,Hunt IM,Silman AJ.Role of mechanical Sweden-a 10 month follow-up study.In:Luczak H,Cakir and psychosocial factors in the onset of forearm pain: AE,Cakir G,eds.WWDU 2002-World Wide Work. prospective population based study.Br Med y 2000;321: Proceedings of the 6th International Scientific Conference on 1-5. 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