B.M. Blatter

Should office workers spend fewer hours at their computer? A systematic review of the literature

Worldwide, millions of office workers use a computer. Reports of adverse health effects due to computer use have received considerable media attention. This systematic review summarises the evidence for a relationship between the duration of work time spent using the computer and the incidence of hand–arm and neck–shoulder symptoms and disorders. Several databases were systematically searched up to 6 November 2005. Two reviewers independently selected articles that presented a risk estimate for the duration of computer use, included an outcome measure related to hand–arm or neck–shoulder symptoms or disorders, and had a longitudinal study design. The strength of the evidence was based on methodological quality and consistency of the results. Nine relevant articles were identified, of which six were rated as high quality. Moderate evidence was concluded for a positive association between the duration of mouse use and hand–arm symptoms. For this association, indications for a dose–response relationship were found. Risk estimates were in general stronger for the hand–arm region than for the neck–shoulder region, and stronger for mouse use than for total computer use and keyboard use. A pathophysiological model focusing on the overuse of muscles during computer use supports these differences. Future studies are needed to improve our understanding of safe levels of computer use by measuring the duration of computer use in a more objective way, differentiating between total computer use, mouse use and keyboard use, attaining sufficient exposure contrast, and collecting data on disability caused by symptoms.

Psychosocial work characteristics in relation to neck and upper limb symptoms

&NA; The aim of this study was to investigate the relationship between psychosocial work characteristics and neck and upper limb symptoms and to examine to what extent this relationship could be explained by other risk factors. Data were used from a prospective cohort study in a working population, with a follow‐up period of 3 years. The 3‐year cumulative incidence rates of neck or upper limb symptoms, neck/shoulder symptoms and elbow/wrist/hand symptoms were 32, 24 and 15%, respectively. After adjustment for potential confounders high job demands was identified as a risk factor for neck/shoulder symptoms (RR: 2.1; CI: 1.2–3.6) and elbow/wrist/hand symptoms (RR: 1.9; CI: 1.0–3.7), and low social support of co‐workers was identified as a risk factor for elbow/wrist/hand symptoms (RR: 2.2; CI: 1.0–4.9). Partly, but not exclusively, these relationships were intermediated by an increased exposure to physical risk factors and increased stress symptoms. Personal characteristics did not considerably influence the main effects of the identified risk factors.

Effect of sporting activity on absenteeism in a working population

Objectives: To determine the effects of sporting activity on absenteeism in a working population. Methods: Data were used from a prospective cohort study in a working population with a follow up period of 3 years and were collected with yearly questionnaires or collected from company records. Complete data on absenteeism, sporting activity, and potential confounders were collected for 1228 workers. ANOVA was used to test differences in frequency and duration of absenteeism, correlations were computed to measure the association between number of sporting years (divided by age) and frequency and duration of absenteeism, and survival analysis, according to the Cox proportional hazards model, was used to test differences in relative risk at absenteeism and recovery. All analyses were adjusted for age, gender, smoking, and alcohol consumption, and were stratified for employees with sedentary and with more active jobs. Results: ANOVA showed a statistically significant higher mean duration of absenteeism among employees not practicing sports, of approximately 20 days over a period of 4 years. The survival analysis showed an increased relative risk at absenteeism (relative risk (RR) 1.09; confidence interval (CI) 1.01 to 1.18) and a decreased relative risk at recovery (RR 0.90; CI 0.85 to 0.95) for employees not practicing sports. The effect of sporting activity is larger in employees with sedentary work. No associations were found between number of sporting years and absenteeism. Conclusion: Employees practicing sports take sick leave significantly less often than their colleagues not practicing sports, while their periods of sick leave are shorter, especially when their work is sedentary.

Loss of productivity due to neck/shoulder symptoms and hand/arm symptoms: Results from the PROMO-study

IntroductionThe objective of the present study is to describe the extent of productivity loss among computer workers with neck/shoulder symptoms and hand/arm symptoms, and to examine associations between pain intensity, various physical and psychosocial factors and productivity loss in computer workers with neck/shoulder and hand/arm symptoms.MethodsA cross-sectional design was used. The study population consisted of 654 computer workers with neck/shoulder or hand/arm symptoms from five different companies. Descriptive statistics were used to describe the occurrence of self-reported productivity loss. Logistic regression analyses were used to examine the associations.ResultsIn 26% of all the cases reporting symptoms, productivity loss was involved, the most often in cases reporting both symptoms (36%). Productivity loss involved sickness absence in 11% of the arm/hand cases, 32% of the neck/shoulder cases and 43% of the cases reporting both symptoms. The multivariate analyses showed statistically significant odds ratios for pain intensity (OR: 1.26; CI: 1.12–1.41), for high effort/no low reward (OR: 2.26; CI: 1.24–4.12), for high effort/low reward (OR: 1.95; CI: 1.09–3.50), and for low job satisfaction (OR: 3.10; CI: 1.44–6.67). Physical activity in leisure time, full-time work and overcommitment were not associated with productivity loss.ConclusionIn most computer workers with neck/shoulder symptoms or hand/arm symptoms productivity loss derives from a decreased performance at work and not from sickness absence. Favorable psychosocial work characteristics might prevent productivity loss in symptomatic workers.

A comparison of methods for the assessment of postural load and duration of computer use

Aim: To compare two different methods for assessment of postural load and duration of computer use in office workers. Methods: The study population existed of 87 computer workers. Questionnaire data about exposure were compared with exposures measured by a standardised or objective method. Measuring true exposure to postural load consisted of an observation of the workstation design and posture by a trained observer. A software program was used to record individual computer use. Results: Comparing the answers for each item of postural load, six of eleven items showed low agreement (kappa <0.20). For six items the sensitivity was below 50%, while for eight items the specificity was 80% or higher. Computer workers were unable to identify risk factors in their workplace and work posture. On average, computer workers overestimated their total computer use by 1.6 hours. The agreement among employees who reported a maximum of three hours of computer use per day was higher than the agreement among employees with a high duration of computer use. Conclusions: Self-report by means of this questionnaire is not a very reliable method to measure postural load and duration of computer use. This study emphasises that the challenge to develop quick and inexpensive techniques for assessing exposure to postural load and duration of computer use is still open.

Physical capacity in relation to low back, neck, or shoulder pain in a working population

Aims: To investigate the longitudinal relation between physical capacity (isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine) and low back, neck, and shoulder pain. Methods: In this prospective cohort study, 1789 Dutch workers participated. At baseline, isokinetic lifting strength, static endurance of the back, neck, and shoulder muscles, and mobility of the spine were measured in the pain free workers, as well as potential confounders, including physical workload. Low back, neck, and shoulder pain were self-reported annually at baseline and three times during follow up. Results: After adjustment for confounders, Poisson generalised estimation equations showed an increased risk of low back pain among workers in the lowest sex specific tertile of performance in the static back endurance tests compared to workers in the reference category (RR = 1.42; 95% CI 1.19 to 1.71), but this was not found for isokinetic trunk lifting strength or mobility of the spine. An increased risk of neck pain was shown for workers with low performance in tests of isokinetic neck/shoulder lifting strength (RR = 1.31; 95% CI 1.03 to 1.67) and static neck endurance (RR = 1.22; 95% CI 1.00 to 1.49). Among workers in the lowest tertiles of isokinetic neck/shoulder lifting strength or endurance of the shoulder muscles, no increased risk of shoulder pain was found. Conclusions: The findings of this study suggest that low back or neck endurance were independent predictors of low back or neck pain, respectively, and that low lifting neck/shoulder strength was an independent predictor of neck pain. No association was found between lifting trunk strength, or mobility of the spine and the risk of low back pain, nor between lifting neck/shoulder strength or endurance of the shoulder muscles and the risk of shoulder pain.

Software-recorded and self-reported duration of computer use in relation to the onset of severe arm–wrist–hand pain and neck–shoulder pain

Objectives In both science and media, the adverse effects of a long duration of computer use at work on musculoskeletal health have long been debated. Until recently, the duration of computer use was mainly measured by self-reports, and studies using more objective measures, such as software-recorded computer duration, were lacking. The objective of this study was to examine the association between duration of computer use at work, measured with software and self-reports, and the onset of severe arm–wrist–hand and neck–shoulder symptoms. Methods A 2-year follow-up study was conducted between 2004 and 2006 among 1951 office workers in The Netherlands. Self-reported computer duration and other risk factors were collected at baseline and at 1-year follow-up. Computer use at work was recorded continuously with computer software for 1009 participants. Outcome questionnaires were obtained at baseline and every 3 months during follow-up. Cases were identified based on the transition within 3 months of no or minor symptoms to severe symptoms. Results Self-reported duration of computer use was positively associated with the onset of both arm–wrist–hand (RR 1.9, 95% CI 1.1 to 3.1 for more than 4 h/day of total computer use at work) and neck–shoulder symptoms (RR 1.5, 95% CI 1.1 to 2.0 for more than 4 h/day of mouse use at work). The recorded duration of computer use did not show any statistically significant association with the outcomes. Conclusions In the present study, no association was found between the software-recorded duration of computer use at work and the onset of severe arm–wrist–hand and neck–shoulder symptoms using an exposure window of 3 months. In contrast, a positive association was found between the self-reported duration of computer use at work and the onset of severe arm–wrist–hand and neck–shoulder symptoms. The different findings for recorded and self-reported computer duration could not be explained satisfactorily.

Factors associated with the ability and willingness to continue working until the age of 65 in construction workers

ObjectivesThe working population is aging and a shortage of workers is expected in the construction industry. As a consequence, it is considered necessary that construction workers extend their working life. The purpose of this study was to explore factors associated with construction workers’ ability and willingness to continue working until the age of 65.MethodsIn total, 5,610 construction workers that participated in the Netherlands Working Conditions Survey filled out questionnaires on demographics, work-related and health-related factors, and on the ability and willingness to continue working until the age of 65. Logistic regression analyses were applied.ResultsOlder workers were more often able, but less willing, to continue working until the age of 65. Frequently using force, lower supervisor support, lower skill discretion, and the occurrence of musculoskeletal complaints were associated with both a lower ability and willingness to continue working. In addition, dangerous work, occasionally using force, working in awkward postures, lack of job autonomy, and reporting emotional exhaustion were associated with a lower ability to continue working, whereas working overtime was associated with a higher ability. Furthermore, low social support from colleagues was associated with a higher willingness.ConclusionIn addition to physical job demands, psychosocial job characteristics play a significant role in both the ability and willingness to continue working until the age of 65 in construction workers. Moreover, preventing musculoskeletal complaints may support the ability and willingness to continue working, whereas preventing emotional exhaustion is relevant for the ability to continue working.

Observed differences in upper extremity forces, muscle efforts, postures, velocities and accelerations across computer activities in a field study of office workers

This study, a part of the PRedicting Occupational biomechanics in OFfice workers (PROOF) study, investigated whether there are differences in field-measured forces, muscle efforts, postures, velocities and accelerations across computer activities. These parameters were measured continuously for 120 office workers performing their own work for two hours each. There were differences in nearly all forces, muscle efforts, postures, velocities and accelerations across keyboard, mouse and idle activities. Keyboard activities showed a 50% increase in the median right trapezius muscle effort when compared to mouse activities. Median shoulder rotation changed from 25 degrees internal rotation during keyboard use to 15 degrees external rotation during mouse use. Only keyboard use was associated with median ulnar deviations greater than 5 degrees. Idle activities led to the greatest variability observed in all muscle efforts and postures measured. In future studies, measurements of computer activities could be used to provide information on the physical exposures experienced during computer use. Practitioner Summary: Computer users may develop musculoskeletal disorders due to their force, muscle effort, posture and wrist velocity and acceleration exposures during computer use. We report that many physical exposures are different across computer activities. This information may be used to estimate physical exposures based on patterns of computer activities over time.

Effectiveness of an intervention at construction worksites on work engagement, social support, physical workload, and need for recovery: results from a cluster randomized controlled trial.

BackgroundTo prolong sustainable healthy working lives of construction workers, a worksite prevention program was developed which aimed to improve the health and work ability of construction workers. The aim of the current study was to investigate the effectiveness of this program on social support at work, work engagement, physical workload and need for recovery.MethodsFifteen departments from six construction companies participated in this cluster randomized controlled trial; 8 departments (n=171 workers) were randomized to an intervention group and 7 departments (n=122 workers) to a control group. The intervention consisted of two individual training sessions of a physical therapist to lower the physical workload, a Rest-Break tool to improve the balance between work and recovery, and two empowerment training sessions to increase the influence of the construction workers at the worksite. Data on work engagement, social support at work, physical workload, and need for recovery were collected at baseline, and at three, six and 12 months after the start of the intervention using questionnaires.ResultsNo differences between the intervention and control group were found for work engagement, social support at work, and need for recovery. At 6 months follow-up, the control group reported a small but statistically significant reduction of physical workload.ConclusionThe intervention neither improved social support nor work engagement, nor was it effective in reducing the physical workload and need for recovery among construction workers.Trial registrationNTR1278