Laura Punnett

PATH: a work sampling-based approach to ergonomic job analysis for construction and other non-repetitive work.

A high prevalence and incidence of work-related musculoskeletal disorders have been reported in construction work. Unlike industrial production-line activity, construction work, as well as work in many other occupations (e.g. agriculture, mining), is non-repetitive in nature; job tasks are non-cyclic, or consist of long or irregular cycles. PATH (Posture, Activity, Tools and Handling), a work sampling-based approach, was developed to characterize the ergonomic hazards of construction and other non-repetitive work. The posture codes in the PATH method are based on the Ovako Work Posture Analysing System (OWAS), with other codes included for describing worker activity, tool use, loads handled and grasp type. For heavy highway construction, observations are stratified by construction stage and operation, using a taxonomy developed specifically for this purpose. Observers can code the physical characteristics of the job reliably after about 30 h of training. A pilot study of six construction laborers during four road construction operations suggests that laborers spend large proportions of time in nonneutral trunk postures and spend approximately 20% of their time performing manual material handling tasks. These results demonstrate how the PATH method can be used to identify specific construction operations and tasks that are ergonomically hazardous.

Covariation between workplace physical and psychosocial stressors: evidence and implications for occupational health research and prevention

There is increasing interest in distinguishing the effects of physical and psychosocial workplace stressors on the aetiology of work-related musculoskeletal disorders (MSD). Modest associations have been found between psychosocial stressors and MSD, such as intensive load, monotonous work and low job control. Interpretation of these results has been limited by likely covariation between physical and psychosocial stressors. This investigation examined exposure covariation among blue- and white-collar workers employed in a mass production manufacturing environment (N = 410). Physical stressors were assessed from questionnaire and accelerometry. Psychosocial stressors were assessed from questionnaire. Pearson and Spearman correlation coefficients were computed. An exploratory factor analysis procedure identified possible common factors linking specific physical and psychosocial stressors. Moderate to high correlations between some physical and psychosocial stressors showed evidence of covariation both across and within groups. Covariation was strongest among blue-collar production and low-status office workers. Factor analysis results showed considerable shared variance between some physical and psychosocial stressors, such as repetition and job control, suggesting that these disparate stressors manifest from common work organization factors that govern the structure of work. While recognizing the conceptual differences between physical and psychosocial stressors, these results call attention to the strong empirical relationships that can exist between some stressors in the workplace setting. To guard against ambiguous study findings that can occur when exposures are mixed, it is critical that future epidemiologic studies include information about the degree of association between task-level stressors. Future research on work organization determinants of task-level stressors, and their coincident occurrence in jobs with greater specialization, may provide promising new insights into the nature of risk for MSD and effective prevention strategies.

Measuring disability of the upper extremity: a rationale supporting the use of a regional outcome measure.

OBJECTIVE Many existing upper extremity outcome measures have been designed for a specific anatomic site (e.g., shoulder) or a specific disease entity (e.g., carpal tunnel syndrome). The purpose of this paper is to examine whether questionnaire items taken from very specific measures are considered relevant only to that specific region or are applicable to the whole extremity. METHODS Fifteen practicing clinicians categorized a sample of 132 items from existing questionnaires according to whether the items reflected disability specific to an anatomic site or were relevant to the whole extremity. RESULTS Seventy-two percent of the items were categorized as relevant to the extremity as a whole, while only 21% of the items were categorized as specific to an anatomic site. CONCLUSION Items in existing specific upper extremity questionnaires are also relevant to other regions and conditions. This finding is in agreement with kinesiologic and biomechanical theories that the upper extremity acts as a single functional unit. Questionnaires designed for the whole extremity could provide a more practical and still valid measure of upper extremity disability.

38 – Work-Related Musculoskeletal Disorders: Is There a Gender Differential, and if So, What Does It Mean?

Musculoskeletal disorders occur in relation to ergonomic exposures both in men and in women. Work-related musculoskeletal disorders (WMSDs) comprise a heterogeneous group of diagnoses that are often referred to collectively as cumulative trauma disorder, repetitive strain injury, occupational cervicobrachial disorder, or overuse syndrome. Specific clinical syndromes that have been associated with occupational exposure include nerve compression disorders, tendon inflammations and related conditions, disk disorders, and degenerative joint disease. Despite the widespread belief that MSDs disproportionately affect women, the outcomes of these conditions have been examined primarily among men. Analysis of gender as a risk factor for MSDs, or adjusting for gender differences, does not elucidate these issues. Future epidemiologic studies of MSDs should include subjects of both genders to avoid unnecessary constraints on the available exposure contrasts. The associations of musculoskeletal disorders with gender and occupational ergonomic exposures should be assessed separately in order to determine whether women are at increased risk when exposed to the same ergonomic stressors as men. Gender-stratified presentation of data is valuable because it permits examination, rather than smoothing over, of differences in the exposure-response relationships.

Trunk Posture and Back Pain: Identification and Control of Occupational Risk Factors

Abstract Awkward trunk posture during work can be caused by a number of controllable factors, including poor work station layout, inappropriate design of tools and equipment, and/or incorrect work methods. If not eliminated, these postures can cause fatigue and contribute to the development of pain and disorders in the lower back. A computer-aided system was developed to evaluate trunk posture during work by measuring the time spent in neutral and non-neutral postures. This system was used to assess postural risk factors in a case-referent study of back disorders in an automobile assembly plant. The use of non-neutral trunk postures, such as forward flexion, lateral bending, and axial twisting, was associated with reports of back pain. The results of this study suggest that job redesign and/or other methods for controlling non-neutral posture be implemented to reduce the risk of back pain on industrial jobs. A general approach to work station design, based on a mechanical model of the human skeletal syste...

The global burden of occupationally related low back pain: estimates from the Global Burden of Disease 2010 study

Objectives The study was part of the Global Burden of Disease 2010 study and aimed to quantify the burden arising from low back pain (LBP) due to occupational exposure to ergonomic risk factors. Methods Exposure prevalence was based on occupation distribution; estimates of relative risk came from a meta-analysis of relevant published literature. The work-related burden was estimated as disability-adjusted life years (DALYs). Estimates were made for each of 21 world regions and 187 countries, separately for 1990 and 2010 using consistent methods. Results Worldwide, LBP arising from ergonomic exposures at work was estimated to cause 21.7 million DALYs in 2010. The overall population attributable fraction was 26%, varying considerably with age, sex and region. 62% of LBP DALYs were in males—the largest numbers were in persons aged 35–55 years. The highest relative risk (3.7) was in the agricultural sector. The largest number of DALYs occurred in East Asia and South Asia, but on a per capita basis the biggest burden was in Oceania. There was a 22% increase in overall LBP DALYs arising from occupational exposures between 1990 and 2010 due to population growth; rates dropped by 14% over the same period. Conclusions LBP arising from ergonomic exposures at work is an important cause of disability. There is a need for improved information on exposure distributions and relative risks, particularly in developing countries.

A Conceptual Framework for Integrating Workplace Health Promotion and Occupational Ergonomics Programs

Musculoskeletal, cardiovascular, and mental health are all associated with the physical and psychosocial conditions of work, as well as with individual health behaviors. An integrated approach to workplace health-promotion programs should include attention to the work environment, especially in light of recent findings that work organization influences so-called lifestyle or health behaviors. Macroergonomics provides a framework to improve both physical and organizational features of work and, in the process, to empower individual workers. The Center for the Promotion of Health in the New England Workplace (CPH-NEW) is a research-to-practice effort examining the effectiveness of worksite programs that combine occupational safety and health—especially /sc>ergonomics—with health promotion, emphasizing the contribution of work organization to both. Two intervention studies are underway in three different sectors: health care, corrections, and manufacturing. Each study features participatory structures to facilitate employee input into health goal-setting, program design and development, and evaluation, with the goal of enhanced effectiveness and longer-term sustainability.

Physical and psychosocial factors related to low back pain during a 24-year period. A nested case-control analysis.

Study Design. A retrospective nested case–control study. Objectives. To identify occupational factors related to low back pain, and to study how interactions between psychosocial and physical factors, and between work-related and leisure-related factors affect low back pain in women and men. Summary of Background Data. A cohort of 484 subjects drawn from the general population was examined in 1969 and 1993, with a focus on occupational working conditions and musculoskeletal disorders. Methods. Information about the physical and psychosocial working conditions and low back pain during the period 1970 to 1993 was collected retrospectively. Odds ratios and confidence intervals were calculated for different potential risk factors. Results. During the 24-year period, 46% of the subjects became patients with low back pain. Among women, heavy physical workload, sedentary work, smoking, and the combination of whole-body vibrations and low influence over work conditions were associated with an excess risk of low back pain. Among men, excess risk for low back pain was seen in heavy physical workload, sedentary work, high perceived load outside work, and the combination of poor social relations and overtime. Conclusions. Factors at work were seen to be risk indicators for low back pain among both genders. Low influence over work conditions among women and poor social relations at work among men, in combination with other factors, seem to be of high relevance for the occurrence of low back pain.

Ergonomic stressors and upper extremity disorders in vehicle manufacturing : cross sectional exposure-response trends

OBJECTIVE: To evaluate the association between upper extremity soft tissue disorders and exposure to preventable ergonomic stressors in vehicle manufacturing operations. METHODS: A cross sectional study was conducted in one vehicle stamping plant and one engine assembly plant. A standardised physical examination of the upper extremities was performed on all subjects. An interviewer administered questionnaire obtained data on demographics, work history, musculoskeletal symptoms, non-occupational covariates, and psycho-physical (relative intensity) ratings of ergonomic stressors. The primary exposure score was computed by summing the responses to the psychophysical exposure items. Multivariate regression analysis was used to model the prevalence of disorders of the shoulders or upper arms, wrists or hands, and all upper extremity regions (each defined both by symptoms and by physical examination plus symptoms) as a function of exposure quartile. RESULTS: A total of 1315 workers (85% of the target population) was examined. The prevalence of symptom disorders was 22% for the wrists or hands and 15% for the shoulders or upper arms; cases defined on the basis of a physical examination were about 80% as frequent. Disorders of the upper extremities, shoulders, and wrists or hands all increased markedly with exposure score, after adjustment for plant, acute injury, sex, body mass index, systemic disease, and seniority. CONCLUSIONS: Musculoskeletal disorders of the upper extremities were strongly associated with exposure to combined ergonomic stressors. The exposure-response trend was very similar for symptom cases and for physical examination cases. It is important to evaluate all dimensions of ergonomic exposure in epidemiological studies, as exposures often occur in combination in actual workplaces.

Risk factors for neck and shoulder disorders: A nested case–control study covering a 24-year period

BACKGROUND In 1969 a population-based study was conducted in the Stockholm region. From the 2,579 randomly selected participants (18-65 years of age in 1969), the youngest subset were asked to participate in a reexamination in 1993. Information regarding working conditions, conditions outside work, and neck and shoulder disorders was collected retrospectively for the period 1970-1993. METHODS Of 783 eligible subjects (42-59 years of age in 1993), 484 responded. Cases of neck/shoulder disorders were defined by past sick leave or medical attention or recent symptoms, depending on available information. For each case (n = 271) two controls were randomly selected, matched by age and gender. Variables regarding both physical and psychosocial conditions were included in the matched analyses. RESULTS Among women mainly psychosocial factors and among men mainly physical factors were associated with neck/shoulder disorders. The only gender common risk indicator found was repetitive hand work (OR approximately 1.5). Interactive effects were also observed. CONCLUSIONS The impact on neck/shoulder disorders from separate factors was moderate but combinations of physical and psychosocial factors, as well as of work-related and non-work-related factors, produced relative risks above 2.