Interactions between physical and psychosocial risk factors at work increase the risk of back disorders: an epidemiological approach

Cross-sectional investigation of task demands and musculoskeletal discomfort among restaurant wait staff

A cross-sectional study of task demands and musculoskeletal discomfort among a sample of 100 wait staff in ten casual dining restaurants was conducted. In addition to answering a questionnaire about musculoskeletal discomfort and symptoms experienced in the past 12 months and attributed to work, subjects were asked about various aspects of their jobs, such as shift length, number of shifts per week and safety training. The managers of the restaurants were also interviewed to gather basic information on factors such as work hours, alternative duty availability and safety practices. When asked to rank the three most important causes of injuries, the responses of both managers and wait staff were congruent with Bureau of Labor Statistics (USA) data for 1999 on the nature of injuries and attributed exposures, with slips and falls, musculoskeletal disorders and acute injuries (e.g. burns, cuts) highlighted. Of the 100 subjects, 42% reported experiencing musculoskeletal symptoms in the past year, with the lower back area (18%) and shoulder (11%) with the most frequent symptoms reported in the responses. Although many of the materials handling tasks were not excessive, the heavier tray lifts and carries are a cause for concern. There are also slip and fall issues that influence the risks of these tasks. Future research needs, including addressing the mismatch between more common materials handling assessment tools and the nature of food serving tasks, are discussed.

Workplace stress, lifestyle and social factors as correlates of back pain: a representative study of the German working population

OBJECTIVES

To investigate the prevalence of back pain in the German working population and the relationship between back pain and workplace stresses, lifestyle and social factors.

METHODS

The first National Health Survey of the Federal Republic of Germany was carried out between October 1997 and March 1999. It comprised a representative epidemiological cross-sectional study of the working population, with a total sample of 3,488 persons between the ages of 18 and 69 years. The participants took part in a medical examination and answered a self-rating questionnaire. The relationship between subjective back pain and workplace stresses and social and lifestyle factors was investigated with bivariate tests and multiple logistical regression analyses.

RESULTS

The 7-day prevalence for back pain in the German working population was found to be 34%, and the 1-year prevalence was 60%. The odds ratios were significantly higher in women, persons of lower socioeconomic status, married and depressed persons and non-athletes. Carrying heavy loads or maintaining a single working posture were the most significant work-related correlates of back pain, for members of both the female and male working population, while environmental stress and psychological stress correlated significantly with back pain in men only.

CONCLUSIONS

This study reports the first representative epidemiological prevalence data for back pain, and its correlates and potential risk factors, for the German working population. To reduce the negative impact of back pain the most promising behavioural and conditional prevention measures in the workplace would be to reduce carrying stress and to vary working posture. In addition, a more active, athletic lifestyle, plus the avoidance of being overweight, should provide an additional protective or preventive effect.

Impact of occupational stress and other psychosocial factors on musculoskeletal pain among Chinese offshore oil installation workers

AIMS

To explore the relation between psychosocial factors and musculoskeletal pain in Chinese offshore oil installation workers.

METHODS

Half of all offshore workers (being a representative sample) in a Chinese oil company were invited to complete a self-administered questionnaire providing information on sociodemographic characteristics, occupational stressors, type A behaviour, social support, coping style, health related behaviour, past injuries, and musculoskeletal pain. Factor analysis was used to identify the sources of occupational stress and the domains of type A behaviour and coping style. Logistic regression analyses were used to study the relations between psychosocial factors and musculoskeletal pain in each body region.

RESULTS

The prevalence of musculoskeletal pain over the previous 12 months varied between 7.5% for elbow pain and 32% for low back pain; 56% workers had at least one complaint. Significant associations were found between various psychosocial factors and musculoskeletal pain in different body regions after adjusting for potential confounding factors. Occupational stressors, in particular stress from safety, physical environment, and ergonomics, were important predictors of musculoskeletal pain, as was coping by eating behaviour.

CONCLUSIONS

These observations supported the widely accepted biopsychosocial model of musculoskeletal disorders and suggested that in future studies of work related musculoskeletal disorders, psychosocial factors must be given due consideration.

Dose-response relations between occupational exposures to physical and psychosocial factors and the risk of low back pain

AIMS

To assess dose-response relations between occupational exposures to physical and psychosocial factors and the risk of low back pain.

METHODS

A cohort of 523 subjects, working in nursing homes and homes for the elderly, was followed prospectively for one year. Physical load for different occupations was assessed by quantitative observations at the workplace. Information on low back pain and other factors was gathered with questionnaires administered at baseline and at one year. Two outcome measures of low back pain incidence were used: any new episode of pain lasting for at least a few hours during follow up (LBP); and any new episode of disabling pain that interfered with daily activities during follow up (LBP/D). Hierarchical regression analysis with a spline function was used to estimate dose-response relations.

RESULTS

The risk of LBP was not associated with physical factors, controlling for confounders; but this outcome was inversely associated with age and weakly, though imprecisely, associated with two psychosocial factors--low decision authority and high work demands. In contrast, the risk of LBP/D was positively associated with age and not associated with the psychosocial factors. Trunk flexion over 45 degrees was monotonically associated with the risk of LBP/D; the estimated relative risk was 3.18 (95% CI 1.13 to 9.00) for 1 hour and 45 minutes of bending per week (90th centile), relative to 30 minutes per week. The hierarchical estimates of effect were more stable than were the maximum likelihood estimates.

CONCLUSION

Occupational exposure to trunk flexion over 45 degrees appears to be a risk factor for low back pain with disability among persons employed in nursing homes and homes for the elderly in the Netherlands.

Work-related musculoskeletal problems among women workers in the semiconductor industry in Peninsular Malaysia

A cross-sectional study to identify the prevalence of musculoskeletal problems and work-related risk factors was conducted among 906 women semiconductor workers. Highest prevalences were pain in the lower limbs, neck/shoulders, and upper back, and highest exposures were prolonged (> or = four hours per workshift) hand/wrist movement, standing, and lifting with hands. After logistic regression, lower-limb pain was significantly associated with standing, neck/shoulder pain with sitting and lifting, upper-back pain with climbing steps, low back pain with hand/wrist movement, and hand/wrist pain with lifting. Neck/shoulder pain was significantly higher for workers with shorter working durations, while lower-limb pain was significantly higher for workers with longer working durations. End-of-line assembly workers had significantly higher odds ratios for pain at all sites, while middle-of-line workers had higher odds ratios for pain in neck/shoulders and upper back, and wafer-fabrication workers had higher odds ratios for pain in low back and lower limbs.

Ergonomic Pain--Part 2: Differential Diagnosis and Management Considerations

Work-related musculoskeletal disorders (MSDs) can produce ergonomic pain in several different regions of the body, including the shoulder, elbow, wrist and hand, lumbar spine, knee, and ankle/foot. Each family of disorders is distinctive in presentation and requires diagnosis-specific interventions. Because of the complex nature of these disorders, management approaches may not always eliminate symptoms and or completely restore patient function to a level found prior to symptom onset. As a consequence, ergonomic measures should be implemented to reduce the overload on tissue and contribute to patient recovery. However, functional limits may persist and the clinician must make further decisions regarding a person's functional status in the chronic stages of the patient's care.

Prevalence, incidence, and recurrence of low back pain in scaffolders during a 3-year follow-up study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To describe the natural history of low back pain by its prevalence, incidence, and recurrence during a 3-year period and identify risk factors for cumulative incidence and recurrence of low back pain in scaffolders.

SUMMARY OF BACKGROUND DATA

Although some studies have described prevalence, incidence, or recurrence of low back pain, few studies have assessed two or more of these outcome measures simultaneously. Furthermore, little is known about the association between individual, physical, psychosocial, and health-related risk factors and cumulative incidence and recurrence of low back pain in scaffolders.

METHODS

Between 1998 and 2001, a cohort of 288 scaffolders (response 85%) completed a questionnaire at baseline and at three yearly follow-ups during 3 years.

RESULTS

At baseline 60% of the study population had had an episode of low back pain in the past 12 months of which 22% was of chronic nature. During follow-up, the yearly incidence of low back pain varied between 20% and 28%, while yearly recurrence rates were 64% to 77%. Only few workers consistently reported the presence (20%) or absence (26%) of low back pain each year. Weak significant associations were present for the following: age 35 to 44 years, moderate general health, high strenuous arm movements, and body mass index with the cumulative incidence of low back pain. Significant associations were found between high manual handling of material and high job demand and low job control and the cumulative recurrence of low back pain, while moderate general health only showed a weak significant association with this outcome measure.

CONCLUSIONS

Low back pain was a dynamic process with high rates for incidence, recurrence, and recovery. General health and work-related physical and psychosocial factors influenced both the incidence and recurrence of low back pain. The incidence and recurrence of low back pain depend strongly on the recall period of low back pain and the time-window of investigation.

Seeking Care for Neck/Shoulder Pain: A Prospective Study of Work-Related Risk Factors in a Healthy Population

This study estimated the 5-year cumulative incidence of neck/shoulder pain and identified work-related risk factors leading subjects to seek care for this problem. Four to six years after the case-referent MUSIC-Norrtälje Study, a postal questionnaire was sent to the referents of this study, and 81% responded. At baseline, 516 men and 697 women were assessed as to their work-related exposures. The 4- to 6-year cumulative incidence for seeking care for neck/shoulder pain was 29% for women and 18% for men. For men, moderately increased risks were found for manual handling, night work/shift work, hindrances at work, and solitary work. For men, the risk increased with an increasing number of risk indicators. No work-related risk factors were found for women, highlighting the difficulty of identifying risk factors in a general population.

Determination of the usage of body mechanics in clinical settings and the occurrence of low back pain in nurses

This explorative study was designed to identify the usage of body mechanics in clinical settings and the occurrence of low back pain in nurses. The sample was composed of 56 nurses who work on the medical, surgical, emergency and intensive care units of a state hospital in Bolu, Turkey. Data collected through observation and interviews were evaluated using percentages, Chi-square and Mann-Whitney U tests. Results of the study showed that the majority of the nurses (87.5%) experienced low back pain at some time in their lives. Among the contributing factors for back pain, the relationship between wearing high heels, heavy lifting and back pain was significant statistically. According to the observations, the majority of the nurses used body mechanics correctly while sitting (53.6%), standing (58.7%), carrying (64.3%), pulling or pushing (79.4%), moving the patient to the side of the bed without an assistant (53.4%), moving the patient to a sitting position in bed (71.4%) and assisting the patient to a standing position (66.6%). However 57.1% of the nurses lifted and 82% extended incorrectly. The conclusion from this research was that some of the nurses do not use body mechanics correctly and the majority have low back pain.

Trapezius muscle motor unit activity in symptomatic participants during finger tapping using properly and improperly adjusted desks

Work-related musculoskeletal disorders in the neck-shoulder area and upper extremities are common among computer users, especially women. We compared temporal changes of motor unit (MU) activation in the trapezius muscle during finger tapping using both appropriate and inappropriate ergonomic desk adjustments. Sixteen intensive and nonintensive computer users with either moderate or severe musculoskeletal disorders participated in the study. Six-channel intramuscular electromyographic (EMG) signals and 2-channel surface EMG were recorded from 2 positions of the trapezius muscle. A statistically significant increase in activity was observed with a desk adjusted 5 cm higher than appropriate and was attributable mainly to increased duration of MU activity. Participants with severe symptoms activated more MUs, and these were also active longer. In women, on average, MUs were active nearly twice as long as in men during the same tapping task. This study demonstrates that it is possible to evaluate ergonomic topics on the MU level and that incorrectly adjusted office equipment, in addition to motor demands imposed by the work task, results in prolonged activity of MUs. A potential application of this research is an increased awareness that certain individuals who work with incorrectly adjusted office equipment may be at greater risk of developing work-related musculoskeletal disorders.

Psychosocial risk factors for musculoskeletal symptoms among women working in geriatric care

BACKGROUND

Nursing is a stressful, physically demanding occupation and a rush setting for musculoskeletal problems. The aim of this study is to explore the extent of the association between psychosocial work characteristics and musculoskeletal symptoms among women working in geriatric care.

METHODS

The participants were female employees of all geriatric nursing homes and geriatric hospital wards in Iceland having a staff of 10 or more. A total of 1,886 questionnaires were distributed. The response rate was 80%.

RESULTS

Finding the job mentally difficult, mental exhaustion after one's shift, dissatisfaction with supervisors or the flow of information, insufficient influence at work, dissatisfaction with the hierarchy, intense time pressure, lack of solidarity, dissatisfaction with the job, harassment, violence or threats at work; all of the aforementioned gave crude odds ratios (OR) two or above for one or more musculoskeletal symptoms. Mental exhaustion and harassment, violence, and threats were the factors connected with symptoms from all the body regions studied.

CONCLUSIONS

The extent of the association of work-related psychosocial factors and musculoskeletal symptoms among the geriatric female nursing staff is substantial and needs to be taken into account by occupational health services and others involved in preventive work. Am. J. Ind. Med. 44:679-684, 2003.

A participatory approach to the study of lifting demands and musculoskeletal symptoms among Hong Kong workers

AIMS

To investigate the use of a worker based methodology to assess the physical stresses of lifting tasks on effort expended, and to associate this loading with musculoskeletal outcomes (MO).

METHODS

A cross sectional study was conducted on 217 male manual handling workers from the Hong Kong area. The effects of four lifting variables (weight of load, horizontal distance, twisting angle, and vertical travel distance) on effort were examined using a linguistic approach (that is, characterising variables in descriptors such as "heavy" for weight of load). The numerical interpretations of linguistic descriptors were established. In addition, the associations between on the job effort and MO were investigated for 10 body regions including the spine, and both upper and lower extremities.

RESULTS

MO were prevalent in multiple body regions (range 12-58%); effort was significantly associated with MO in 8 of 10 body regions (odds ratios with age adjusted ranged from 1.31 for low back to 1.71 for elbows and forearm). The lifting task variables had significant effects on effort, with the weight of load having twice the effect of other variables; each linguistic descriptor was better described by a range of numerical values rather than a single numerical value.

CONCLUSIONS

The participatory worker based approach on musculoskeletal outcomes is a promising methodology. Further testing of this approach is recommended.

Risk factors for sickness absence because of low back pain among scaffolders: a 3-year follow-up study

STUDY DESIGN

A prospective cohort study was conducted.

OBJECTIVE

To find risk factors for short-term (<or=14 days) and long-term (>14 days) sickness absence because of low back pain among scaffolders.

SUMMARY OF BACKGROUND DATA

Although some studies have described the relation between work-related risk factors for musculoskeletal disease and sickness absence, little is known about the role of individual, physical, and psychosocial factors and different end points of low back pain as risk factors for sickness absence among scaffolders.

METHODS

Between 1998 and 2001, 222 scaffolders and 66 supervisors (response rate, 86%) completed a questionnaire at baseline. In addition, data on sickness absence were collected from absence records.

RESULTS

At baseline, 60% of the study population had experienced an episode of low back pain in the 12 months preceding the investigation, 37% of which were of chronic nature. During the follow-up period, 34% of the population had been on sick leave for at least one episode of low back pain. The risk factors for sickness absence less than 2 weeks were a high physical load from strenuous arm movements and severe low back pain. Workers with severe low back pain were at higher risk for sickness absence longer than 2 weeks. Psychosocial workload and individual characteristics did not predict the occurrence of sickness absence because of low back pain.

CONCLUSIONS

Because work-related physical load was a risk factor for sickness absence less than 2 weeks and severe low back pain was a risk factor for sickness absence both shorter than and longer than 2 weeks, a focus on secondary prevention for scaffolders with severe low back pain is advised.

Individual and combined impacts of biomechanical and work organization factors in work-related musculoskeletal symptoms

BACKGROUND

Investigations of work-related low back (LB) and upper extremity (UE) disorders have increasingly utilized multivariable models that include biomechanical/physical and work organization factors. However, the nature of any interactive effects is not well understood.

METHODS

Using questionnaires, high and low exposure groups for biomechanical/physical factors, cognitive demands, cognitive processing, interpersonal demands, participatory management, skill discretion, and time pressure for 289 individuals (U.S. Marines) were identified. Musculoskeletal symptom status was also determined by questionnaire. Individual and biomechanical-psychosocial combinations were examined in adjusted multivariable logistic regression analyses.

RESULTS

Time pressure was associated with both LB and UE symptoms (odds ratio(s) (OR) range = 2.13-3.09), while higher biomechanical exposures were risk factors for LB symptoms (OR = 2.07; 95% confidence intervals (CI): 1.00-4.35) and concurrent LB and UE symptoms (OR = 2.80; CI: 1.35-5.83). Greater risks for concurrent LB and UE symptoms were indicated for combinations involving higher biomechanical exposure and: time pressure (OR = 2.21; CI: 1.19-4.10); cognitive demands (OR = 2.25; CI: 1.23-4.09); cognitive processing (OR = 2.08; CI: 1.16-3.75); interpersonal demands (OR = 2.44; CI: 1.35-4.41); participatory management (OR = 2.50; CI: 1.30-4.81). Results did not suggest any interaction between biomechanical and work organization factors.

CONCLUSIONS

While no synergism was indicated, the present findings emphasize the need to consider both biomechanical factors and specific work organization factors, particularly time pressure, in reducing musculoskeletal-related morbidity.

Work-system risk factors for permanent work disability among home-care workers: a case-control study

OBJECTIVE

There is a growing need for home-care services in western societies. As home-care workers show high levels of absence related to poor health it is important that we broaden our knowledge about what factors in the work system contribute to this. The aim of this study was to explore and estimate the impact of the work system on permanent work disability and its relative importance compared with home-life risks among home-care workers.

METHODS

The cases (617 subjects) were all home-care workers in Sweden, whose disability pension was approved in 1997 or 1998. The controls (771 subjects) were home-care workers still working. We used a questionnaire to gain situation-specific information on working life and home life 5 and 15 years before disability pension entitlement.

RESULTS

The most important risk factors in the work system were poor ergonomic/lifting conditions, time pressure and lack of professional caring technique. Fifteen years prior to disability pension entitlement, insufficient management (odds ratio (OR) 95%, CI 2.6[1.6;4.2]) and relational problems at work were also risk factors. Five years before disability pension entitlement, poor organisational support (4.1 [2.5;6.7]), opportunities for co-working and working climate (3.5 [2.4;5.2]) were also strongly related to a persisting work ability. The magnitude of exposure to a number of risk factors had an increased effect (highest 13.8 [5.6-33.8]). The strongest risk factor in home life was little opportunity to rest from work (4.9 [3.0;8.0]). The risk factors in working life were robust to the inclusion of the grouped risk factors of home life.

CONCLUSIONS

The conclusion was that risk factors related to the work system are, alone, strongly related to permanent work disability among home-care workers. Also, exposure to several of the risk factors constitutes a notably strong risk for permanent work disability.

Organizational climate, perceived work-related symptoms and sickness absence: a population-based survey

Very few reports have been published on organizational climate, health, and sickness absence in a representative sample of the entire workforce. The aim of this study was to determine how the perceived organizational climate of a workplace is related with work-related symptoms and sickness absence and how these factors vary according to sociodemographic and work-related characteristics. Data were collected in computer-assisted telephone interviews of a random sample of 4209 currently employed Finns drawn from the population register. A tense and prejudiced climate was associated with a higher risk of work-related symptoms than a relaxed and supportive climate (odds ratio [OR] 3.0 (95% CI = 2.4-3.7). The corresponding ORs were 4.3 (95% CI = 3.3-5.6) for psychological symptoms, 1.6 (95% CI = 1.2-2.0) for musculoskeletal symptoms, and 1.6 (95% CI = 1.3-2.1) for more than the average number of sick-leave days. Part of the impact of organizational climate on sickness absence is not caused by an increase in work-related symptoms. Thus, organizational climate seems not only to correspond with organizational practices and leadership but also occupational health. Organizational climate could be used as a research tool in attempts to reduce work-related ill health and sickness absenteeism.

The impact of mental processing and pacing on spine loading: 2002 Volvo Award in biomechanics

STUDY DESIGN

The impact of various levels of mental processing and pacing (during lifting) on spine loading was monitored under laboratory conditions.

OBJECTIVES

To explore how mental demands and pacing influence the biomechanical response and subsequent spine loading and, to determine whether individual characteristics have a modifying role in the responses.

SUMMARY OF BACKGROUND DATA

Modern work often requires rapid physical exertions along with demands of mental processing (both psychosocial stressors). While the effect of physical workplace factors on spine loading has been widely documented, few studies have investigated the impact that interaction of psychosocial factors and individual factors has on spine loads.

METHODS

For this study, 60 subjects lifted boxes while completing two types of mental processing tasks: 1) series tasks with decisions occurring before the act of lifting, and 2) simultaneous tasks with decisions occurring concurrently with the lift. For both of these mental processing conditions, two intensities of mental load were evaluated: simple and complex. Task pacing was also adjusted under slow and fast conditions. Finally, individual characteristics (personality and gender) were evaluated as potential modifiers. An electromyographically assisted model evaluated the three-dimensional spine loads under the experimental conditions.

RESULTS

Simultaneous mental processing had the largest impact on the spine loads, with the complex intensity resulting in increases of 160 N with lateral shear, 80 N with anteroposterior shear, and 700 N with compression. Increased task pace produced greater lateral shear (by 20 N), anteroposterior shear (by 60 N), and compression loads (by 410 N). Gender and personality also influenced loadings by as much as 17%.

CONCLUSIONS

Mental processing stress acted as a catalyst for the biomechanical responses, leading to intensified spine loading. Mental stress appeared to occur as a function of time pressures on task performance and resulted in less controlled movements and increases in trunk muscle coactivation. These adjustments significantly increased spine loading. These results suggest a potential mechanism for the increase in low back pain risk resulting from psychosocial stress caused by modern work demands.

The nature of work-related neck and upper limb musculoskeletal disorders

The nature of work-related musculoskeletal disorders of the neck and upper limbs is reviewed using both scientific data and the consensus view of experts, union bodies and government agencies across the European Union. Work-related musculoskeletal disorders describe a wide range of inflammatory and degenerative diseases and disorders. These conditions result in pain and functional impairment and may affect, besides others, the neck, shoulders, elbows, forearms, wrists and hands. They are work-related when the work activities and work conditions significantly contribute to their development or exacerbation but are not necessarily the sole determinant of causation. The classification and the need for standardised diagnostic methods for assessment of neck and upper limb musculoskeletal disorders are reviewed. These disorders are a significant problem within the European Union with respect to ill health, productivity and associated costs. The pathomechanisms of musculoskeletal disorders affecting tendons, ligaments, nerves, muscle, circulation and pain perception are reviewed and conceptual models for the pathogenesis of musculoskeletal disorders affecting the neck and upper limbs are presented. The epidemiological evidence on the work-relatedness of these disorders is discussed. A relationship between the performance of work and the occurrence of neck and upper limb musculoskeletal disorders is evident. Intervention strategies in the workplace for the reduction of both exposure and effect should focus upon factors within the work organisation as well as actively involving the individual worker. The current knowledge is sufficient to enable informed decisions to be made on future research needs and prevention strategies at the societal, organisational and individual level.

Epidemiological study to investigate potential interaction between physical and psychosocial factors at work that may increase the risk of symptoms of musculoskeletal disorder of the neck and upper limb

OBJECTIVES

To investigate potential interactions between physical and psychosocial risk factors in the workplace that may be associated with symptoms of musculoskeletal disorder of the neck and upper limb.

METHODS

891 of 1514 manual handlers, delivery drivers, technicians, customer services computer operators, and general office staff reported on physical and psychosocial working conditions and symptoms of neck and upper limb disorders using a self administered questionnaire (59% return rate). Of the 869 valid questionnaire respondents, 564 workers were classified in to one of four exposure groups: high physical and high psychosocial, high physical and low psychosocial, low physical and high psychosocial, and low physical and low psychosocial. Low physical and low psychosocial was used as an internal reference group. The exposure criteria were derived from the existing epidemiological literature and models for physical and psychosocial work factors. The frequency and amplitude of lifting and the duration spent sitting while experiencing vibration were used as physical exposure criteria. Ordinal values of mental demands, job control, and social support with managers and coworkers were used as psychosocial exposure criteria.

RESULTS

In the multivariate analyses, the highest and significant increase in risk was found in the high physical and high psychosocial exposure group for symptoms of hand or wrist and upper limb disorders after adjusting for years at the job, age, and sex. A potential interaction effect was found for the symptoms of the hand or wrist and upper limb disorders but not for the neck symptoms.

CONCLUSION

This study showed that workers highly exposed to both physical and psychosocial workplace risk factors were more likely to report symptoms of musculoskeletal disorders than workers highly exposed to one or the other. The results suggest an interaction between physical and psychosocial risk factors in the workplace that increased the risk of reporting symptoms in the upper limbs. Psychosocial risk factors at work were more important when exposure to physical risk factors at work were high than when physical exposure was low. Ergonomic intervention strategies that aim to minimise the risks of work related musculoskeletal disorders of the upper limb should not only focus on physical work factors but also psychosocial work factors.

Risk factors associated with the transition from acute to chronic occupational back pain

STUDY DESIGN

A prospective cohort study was conducted on workers claiming earnings-related compensation for low back pain. Information obtained at the time of the initial claim was linked to compensation status (still claiming or not claiming) 3 months later.

OBJECTIVE

To identify individual, psychosocial, and workplace risk factors associated with the transition from acute to chronic occupational back pain.

SUMMARY OF BACKGROUND DATA

Despite the magnitude of the economic and social costs associated with chronic occupational back pain, few prospective studies have investigated risk factors identifiable in the acute stage.

METHODS

At the time of the initial compensation claim, a self-administered questionnaire was used to gather information on a wide range of risk factors. Then 3 months later, chronicity was determined from claimants' computerized records.

RESULTS

The findings showed that 3 months after the initial assessment, 204 of the recruited 854 claimants (23.9%) still were receiving compensation payments. A combined multiple regression model of individual, psychosocial, and workplace risk factors demonstrated that severe leg pain (odds ratio [OR], 1.9), obesity (OR, 1.7), all three Oswestry Disability Index categories above minimal disability (OR, 3.1-4), a General Health Questionnaire score of at least 6 (OR, 1.9), unavailability of light duties on return to work (OR, 1.7), and a job requirement of lifting for three fourths of the day or more all were significant, independent determinants of chronicity (P < 0.05).

CONCLUSIONS

Simple self-report measures of individual, psychosocial, and workplace factors administered when earnings-related compensation for back pain is claimed initially can identify individuals with increased odds for development of chronic occupational disability.

Interrelations of risk factors and low back pain in scaffolders

OBJECTIVES

To assess with a cross sectional study the interrelations between physical, psychosocial, and individual risk factors and different end points of low back pain.

METHODS

In total, 229 scaffolders and 59 supervisors completed a questionnaire about manual handling of materials, awkward back posture, strenuous arm position, perceived exertion, psychosocial load, need for recovery, and general health. Physical load at the worksite was also measured with many frequent observations. Interrelations between risk factors and their relation with four end points of low back pain were investigated.

RESULTS

Interrelations were strong among self reported determinants of physical load but showed an inverted trend for both age and total working experience, which could indicate the presence of a healthy worker effect. Weak relations existed between variables of psychosocial and physical load. The multivariate analyses showed a significant relation between high manual handling of materials, moderate perceived general health, high job demands, and low back pain in the past 12 months. Chronic low back pain was significantly correlated with high perceived exertion and moderate perceived general health. Severe low back pain was significantly correlated with awkward back postures, high need for recovery, and high job demands. Finally, low back pain with perceived disability was significantly related to strenuous shoulder positions and moderate perceived general health. All end points of low back pain were consistently associated with physical load whereas psychosocial aspects showed a more diverse pattern.

CONCLUSIONS

The findings of this study suggest that work related risk factors may vary according to different definitions of low back pain. Distinct patterns of risk factors might enhance different expressions of it. Scaffolders are a group at high risk of developing persistent forms of low back pain.

The Boeing prospective study and beyond

STUDY DESIGN

The Boeing prospective study was reviewed. The Boeing prospective study, comprising two articles, was a large field study that explored why workers would or would not report occupational back pain problems.

OBJECTIVES

The most immediate objective was to determine the extent to which conclusions drawn from the Boeing prospective study withstand critical examination. The ultimate purpose of this review was to develop guidelines for field studies of back pain in industry.

SUMMARY OF BACKGROUND DATA

For more than a century, researchers have noted great variability among individuals in the reporting of back pain, but the explanations posed for this variability have been inconsistent. Because findings gain credibility roughly to the extent that they bear on the world outside the laboratory, field studies in particular hold great potential for clarifying the underlying explanation for individual variability in back pain reporting. The Boeing prospective study was a large and ambitious field study that examined this issue.

METHODS

The Boeing prospective study was examined through the lens of research conducted since it was published. The review used both the methodological and substantive literature.

RESULTS

The Boeing prospective study, based on a minority of workers originally solicited to participate in it (33-41%), accounted for 7% of the variation in why workers would or would not report a back pain problem. A number of issues that may have biased its results toward the null are examined.

CONCLUSIONS

The highlighting of the Boeing prospective study's limitations may be instructive not so much to criticize this one particular study but, rather, to anticipate problems that in general may be encountered in field studies of back pain in industry. Looking beyond the Boeing prospective study, the following guidelines for the conduct of such studies may be proposed: 1) Study designs should be based on explanations from which testable hypotheses may be derived; 2) Subgroups within the more general category of "back pain" should be delineated; 3) Both occupational exposures and psychosocial factors should be entered into the analysis; 4) Factors not apparent at the workplace should be considered; 5. Abstracts of articles should be carefully crafted.

The impact of psychosocial work factors on musculoskeletal pain: a prospective study

A prospective cohort study investigated how psychosocial work factors predict musculoskeletal pain. A total of 721 workers at 226 automobile repair garages answered two questionnaires distributed with a 1-year interval. The predictor variables were psychological demands, decision authority, social support, and management support. The outcome variables were neck pain, low back pain, and an index of pain from seven different parts of the body in the past 30 days. The best predictors were low decision authority and management support. Low decision authority predicted neck pain, low back pain, and total musculoskeletal pain when adjusted for the effect of the respective musculoskeletal pain measured in the first survey, for age, and for gender. Low management support predicted both low back pain and general musculoskeletal pain. The study indicates that psychosocial factors at work may predict musculoskeletal pain.