Risk factors for first-ever low back pain among workers in their first employment

BACKGROUND: Low back pain has been estimated to be the most costly ailment of people of working age. Both work characteristics and individual factors have been identified as risk factors. The first interaction between work characteristics and individual factors occurs when workers start in their first job. AIMS: To investigate work-related risk factors for first-ever low back pain in young workers in their first employment. METHODS: A cross-sectional analysis was performed on 278 young workers in their first employment and without a history of low back pain prior to working. Work-related physical factors, psychosocial work characteristics, individual variables and first-ever low back pain were queried by means of a questionnaire. RESULTS: About half of the workers who developed low back pain after job start did so in the first year of employment. An increased risk was observed for (i) long periods of seated work [relative risk (RR) = 3.2, 95% confidence interval (CI) = 1.6-6.4]; (ii) more than 12 flexion or rotation movements of the trunk per hour (RR = 3.0, 95%CI = 1.4-6.4); and (iii) more than 3 years seniority in a job involving lifting more than 25 kg at least once an hour (RR = 3.7, 95%CI = 1.4-9.4). As to psychosocial work characteristics, first-ever low back pain was associated with a combination of low psychological job demands and low supervisor support. CONCLUSION: Work-related physical factors and psychosocial work characteristics should be considered as risk factors for first-ever low back pain. First-ever episodes of low back pain are common in the first year of employment. This may reflect a lack of work experience or training.     

Stressful psychosocial work environment increases risk for back pain among retail material handlers

BACKGROUND: Back pain is a major source of lost work time. Occupational physical activity only accounts for a fraction of low back pain; therefore, there is growing interest in investigating other possible causes of back pain including the psychosocial work environment. METHODS: Material handlers (N = 6,311) in 160 newly opened stores were interviewed at study entry and approximately 6 months later. Factor analysis was used to reduce the 37 psychosocial questionnaire items to seven distinct factors. RESULTS: After adjusting for history of back problems and work-related lifting, risk of back pain was moderately increased among employees who reported high job intensity demands (odds ratio (OR) = 1.8), job dissatisfaction (OR = 1.7), and high job scheduling demands (OR = 1.6). CONCLUSIONS: Modification of the psychosocial work environment for material handlers in large retail stores may help reduce back pain among employees.     

Spinal troubles in sewage workers: epidemiological data and work disability due to low back pain

Objectives: To determine the prevalence of spinal troubles (i.e., neck, upper back and low back pain) in a population of sewage workers, and to establish the effect of sociodemographic, work-related, physical, and psychosocial factors on the reported work disability due to low back pain (LBP) during the previous 12 months. Methods: Data from 255 sewage workers were obtained by standardized questionnaire, structured interview, and standardized physical examination. Data on the prevalence of neck, upper back and low back pain were obtained with the use of the Nordic Questionnaire. The level of disability was assessed from a modified Low-Back Outcome Scale. Work history included physical factors and job perception based on a modified Work APGAR Score. Other questionnaires recorded the psychosocial aspects of the work environment. In addition, we compared the risk factors between sewage workers who had been prevented from doing their normal work, at any time during the preceding 12 months, as a result of LBP (n=92), and those without any history of work disability during the previous 12 months (n=157). Results: The 12-month prevalence rates of neck, upper back and low back pain were 52.4%, 54.8%, and 72.8%, respectively. The prevalence of spinal troubles increased with age. Work disability during the preceding 12 months due to LBP was significantly positively associated with age, disability, the weekly duration of stooping and lifting 5 years previously and higher abnormal illness-behavior scores (odds ratio between 1.26 and 0.94). Moreover, when adjusted for age, the results showed that the subjects in the work disability group were more likely to report higher pain intensities, decreased participation in sports activities, higher levels of physical impairment, the belief that their LBP was related to the physical demands of their job, and a lack of drive (P < 0.05). Conclusions: This study revealed a high incidence of spinal troubles among sewage workers. In a multidisciplinary approach, we demonstrated that not one factor alone but a combination of sociodemographic, work-related and psychosocial factors have shown associations with work disabilities due to LBP. Additional studies evaluating the relative importance of individual risk factors are warranted. Received: 12 May 1999 / Accepted: 27 November 1999     

High physical and psychosocial load at work and sickness absence due to neck pain

OBJECTIVES: This study investigates the relationship between physical and psychosocial load at work and sickness absence due to neck pain. METHODS: A prospective cohort study with a follow-up period of 3 years (1994-1998) was performed among a working population. At the beginning of the study, physical load at work was quantified by means of video recordings. Work-related psychosocial variables were measured by means of the Job Content Questionnaire. The frequency of sickness absence due to neck pain with a minimal duration of 3 days was assessed on the basis of company registrations during the follow-up period. Altogether 758 workers were included in the analyses. Possible confounding by individual characteristics, physical load, and psychosocial load was studied. RESULTS: Work-related neck flexion and neck rotation, low decision authority, and medium skill discretion showed statistically significant increased risks for sickness absence due to neck pain (adjusted rate ratios ranging from 1.6 to 4.2). High quantitative job demands, low skill discretion, and low job security showed nonsignificant increased risks for sickness absence due to neck pain (adjusted rate ratios of 2.0, 1.6 and 1.7, respectively). Work-related sitting, conflicting job demands, supervisor support, and co-worker support did not increase sickness absence due to neck pain. CONCLUSION: Work-related neck flexion, neck rotation, low decision authority, and medium skill discretion are risk factors for sickness absence due to neck pain. There are indications that high job demands, low skill discretion, and low job security are also risk factors for sickness absence due to neck pain.     

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.


Keywords: interrelations; low back pain; risk factors     

Musculoskeletal complaints among Italian X-ray technologists

The aim of this study was to determine the prevalence of musculoskeletal complaints among X-ray technologists and to examine their relationship with physical and psychosocial factors. A cross-sectional study was performed in 2006 among 203 X-ray technologists working in 13 hospitals in the Apulia region of southern Italy. A questionnaire was used to collect data on personal characteristics, physical workload, psychosocial aspects, and the presence of musculoskeletal symptoms in the neck, shoulders, low back, hand/wrist and legs. Univariate analyses and multiple logistic regression analyses were then performed. The prevalence of complaints at any body site in the previous 12 months was 67%. Low back pain was the most commonly reported symptom (59.6%), followed by shoulder (21.2%), neck (19.7%), leg (13.8%) and hand/wrist pain (12.3%). Age was associated with low back pain, while high physical workload was associated with symptoms in the neck, low back and hand/wrist. High job demands were associated with neck and shoulder pain. Overall, our study suggests high prevalence rates of musculoskeletal complaints may exist among Italian X-ray technologists. Physical workload, psychosocial and individual factors appear to be important risk factors for musculoskeletal disorders within this occupational group.     

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.     

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

OBJECTIVES: To investigate the possible interactions between physical and psychosocial risk factors at work that may be associated with self reported back disorders. METHODS: 891 of 1514 manual workers, delivery drivers, technicians, customer services computer operators, and general office staff reported risk factors at work and back disorders with a self administered questionnaire (59% return rate). Of the 869 respondents with a valid questionnaire, 638 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 existing epidemiological publications 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 from managers and coworkers were used as psychosocial exposure criteria. RESULTS: The highest increase in risk was found in the high physical and high psychosocial exposure group for symptoms of back disorders. In the crude and multivariate analyses, a departure from an additive risk model was found for the 7 day prevalence of symptoms of a low back disorder and also for a recurrent back disorder not present before the current job but also experienced in the past 7 days. CONCLUSION: This study suggests that an interaction between physical and psychosocial risk factors at work may exist to increase the risk of self reported back disorders. Ergonomic prevention strategies that aim to minimise the risks of symptoms of work related back disorders should not only focus on physical but also on psychosocial risk factors at work. The greatest benefits are likely to be realised when both physical and psychosocial factors are put right.       

Self-Report Measure of Low Back-Related Biomechanical Exposures: Clinical Validation

Low back pain and symptoms are major contributors to ambulatory visits, economic burden, and reduced readiness among military personnel and employers in the civilian workplace as well. While a link between low back pain and biomechanical exposures has been established, efficient surveillance methods of such exposures are still needed. Furthermore, the utility of self-report measures for biomechanical exposures has not been examined extensively. The present cross-sectional study analyzed questionnaire data from US Army soldiers (n = 279) working in previously identified occupational specialties that were associated with high risk for low back pain and/or low back pain disability. Demographic characteristics, physical workload, health behaviors, and psychosocial factors were assessed in addition to self-reported workplace biomechanical exposures using the Job Related Physical Demands (JRPDs). Outcomes included self-reported low back pain severity, low back symptoms, functional limitations, and general physical health. The results indicated that the self-report measure of biomechanical exposure had a high degree of internal consistency (Cronbach alpha, 0.95). The JRPD index correlated with low back symptoms, pain intensity, function, and perceived work load using the Borg scale. Regression analyses indicated statistically significant associations between the JRPD and back pain specific pain severity and physical function, but not for general physical health (SF-12) after controlling for age, gender, educational level, job type, and reported exercise and work stress. Specifically, higher JRPD scores (representing greater biomechanical exposure) were associated with higher levels of pain intensity and functional limitations. Higher JRPD scores were found to place an individual at a greater likelihood for being a case with low back pain within the past 12 months (OR = 1.01 per point increase in scale-95%; range 38–152; CI = 1.00–1.02, p 0.05). While future longitudinal studies of the JRPD determining the predictive validity of the measure are needed, the present study provides evidence of the utility of the JRPD for assessing biomechanical exposures associated with low back pain within high-risk jobs. The findings suggest that the JRPD may assist with surveillance efforts and be useful as a process and/or outcome measure in research related to occupational rehabilitation.     

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.

     

High physical work load and low job satisfaction increase the risk of sickness absence due to low back pain: results of a prospective cohort study

Objective: To determine whether physical and psychosocial load at work influence sickness absence due to low back pain.

Methods: The research was a part of the study on musculoskeletal disorders, absenteeism, stress, and health (SMASH), a 3 year prospective cohort study on risk factors for musculoskeletal disorders. Workers from 21 companies located throughout The Netherlands participated in the part of this study on sickness absence due to low back pain. The study population consisted of 732 workers with no sickness absences of 3 days or longer due to low back pain in the 3 months before the baseline survey and complete data on the reasons for absences during the follow up period. The mean (range) period of follow up in this group was 37 (7–44) months. Physical load at work was assessed by analyses of video recordings. Baseline information on psychosocial work characteristics was obtained by a questionnaire. Data on sickness absence were collected from company records. The main outcome measure was the rate of sickness absences of 3 days or longer due to low back pain during the follow up period.

Results: After adjustment of the work related physical and psychosocial factors for each other and for other potential determinants, significant rate ratios ranging from 2.0 to 3.2 were found for trunk flexion, trunk rotation, lifting, and low job satisfaction. A dose-response relation was found for trunk flexion, but not for trunk rotation or lifting. Non-significant rate ratios of about 1.4 were found for low supervisor support and low coworker support. Quantitative job demands, conflicting demands, decision authority, and skill discretion showed no relation with sickness absence due to low back pain.

Conclusions: Flexion and rotation of the trunk, lifting, and low job satisfaction are risk factors for sickness absence due to low back pain. Some indications of a relation between low social support, either from supervisors or coworkers, and sickness absence due to low back pain are also present.

     

Factors associated with the subject's ability to quantify their lumbar flexion demands at work

Continuous measurements of lumbar posture provide the basis for determining the factors influencing the difference between subjective and objective assessments of lumbar posture. The lumbar flexion posture during an entire work day was registered in a group of 13 sewage workers and 14 physical therapists. Subjective lumbar posture data, perceived occupational stress, job satisfaction and 12 month prevalence of low back pain were obtained using standardized questionnaires. For the entire sample, a significant positive correlation was found between the degree of overestimation of the lumbar bending demands at work and the level of occupational stress (p > 0.01) as well as the low back pain prevalence in the past 12 months. Continuous measurement of spinal posture is an important tool not only for comparisons of posture demands during various activities but also for investigations into the complex interactions between the biomechanical and psychosocial determinants of low back pain.     

Patient clusters in acute, work-related back pain based on patterns of disability risk factors

OBJECTIVE: To identify subgroups of patients with work-related back pain based on disability risk factors. METHODS: Patients with work-related back pain (N = 528) completed a 16-item questionnaire of potential disability risk factors before their initial medical evaluation. Outcomes of pain, functional limitation, and work disability were assessed 1 and 3 months later. RESULTS: A K-Means cluster analysis of 5 disability risk factors (pain, depressed mood, fear avoidant beliefs, work inflexibility, and poor expectations for recovery) resulted in 4 sub-groups: low risk (n = 182); emotional distress (n = 103); severe pain/fear avoidant (n = 102); and concerns about job accommodation (n = 141). Pain and disability outcomes at follow-up were superior in the low-risk group and poorest in the severe pain/fear avoidant group. CONCLUSIONS: Patients with acute back pain can be discriminated into subgroups depending on whether disability is related to pain beliefs, emotional distress, or workplace concerns.     

Risk factors for work-related musculoskeletal disorders in an aluminum smelter

A cross-sectional study of selected jobs in an aluminum smelter was conducted to assess the prevalence of work-related musculoskeletal disorders (WMDs), and to estimate their association with physical and psychosocial characteristics of the jobs. A structured interview and physical exam were used to assess the musculoskeletal health status of the participants, and a self-administered questionnaire was used to assess the psychosocial factors. Observational job analysis was conducted to evaluate 37 potential physical risk factors. Complete data were available for 104 subjects. The prevalence of WMDs on interview and physical exam were 0.8%, 14.9%, 11.6%, 14.9%, and 17.4% for the neck, shoulder, elbow/forearm, hand/wrist, and low back regions, respectively. Unconditional multiple logistic regression was used to model the relationship between physical and psychosocial factors and health status. Years of forearm twisting were found to be a significant predictor for hand/wrist disorders on interview (OR = 17, 95% CI = 2.9–106); for elbow/foream disorders on physical exam and interview (OR = 37, 95% CI = 3.0–470); and for shoulder disorders on interview (OR = 92, 95% CI = 7.3–∞) and on interview and physical exam (OR = 46, 95% CI = 3.8–550). Low decision latitude was also found to be significant for the shoulder on interview (OR = 4.5, 95% CI = 1.3–16). High job satisfaction (OR = 5.9, 95% CI = 1.4–25) and low social support (OR = 5.3, 95% CI = 1.3–22) were associated with low back pain report on interview; only high job satisfaction (OR = 5.3, 95% CI = 1.1–26) was associated with low back pain on both interview and physical exam. Am. J. Ind. Med. 32:66-75, 1997. © 1997 Wiley-Liss, Inc.     

Associations of psychosocial and individual factors with three different categories of back disorder among nursing staff

Although back disorders are a major occupational problem for nursing staff, few studies distinguish different types. By means of a structured questionnaire, we performed a cross-sectional study on the prevalence of diagnosed lumbar disc hernia, chronic low-back pain (LBP) (at least 90 d in the preceding 12 months) and acute LBP (intense pain for at least 1 d) with respect to physical, individual and psychosocial factors among female nurses (n=587), nursing aides (n=228) and head-nurses (n=43) working in a university hospital (95% of the female workforce). Almost all respondents reported known high-risk occupational activities. Overall prevalence of reported back disorders was 44% (acute LBP 19%, chronic LBP 17%, lumbar hernia 8%). On multinomial logistic regression analysis, scoliosis and commonly stress-related psychosomatic symptoms were associated with all three types of back disorder; trauma/fractures of the spine, pelvis and/or legs and a global work-environment/job-satisfaction score with acute LBP; increasing age with lumbar disc hernia. While confirming the relevance of considering different definitions of back disorder, our data indicate items for investigation in cohort studies. These include: identification of specific risk factors for lumbar hernia; avoidance of possible work-environment risk factors such as hurried execution of different tasks at the same time; and influence on job suitability of underlying spinal pathologies such as scoliosis.     

Identifying Work Organization Targets for a Work-Related Musculoskeletal Symptom Prevention Program

While research linking work organization factors to work-related musculoskeletal disorders has been increasing, there is still a need to delineate specific dimensions to be targeted by intervention programs. The present cross-sectional investigation identified work organization risk factors for low back (LB) and upper extremity (UE) symptoms and determined the magnitudes of such associations. Questionnaires containing items on ergonomic, individual psychosocial, and occupational psychosocial factors were administered to a sample of workers (n = 248 U.S. Marines) in previously identified high-risk job categories for musculoskeletal disorders. Study participants were categorized into groups of either having LB symptoms only, UE symptoms only, concurrent LB and UE symptoms, or being asymptomatic on the basis of self-report. Additionally, measures of pain intensity, physical function, and mental health were obtained. Linear regression analyses adjusting for demographics, ergonomic factors, and individual psychosocial factors indicated that decision authority and experienced responsibility for work were significant correlates for pain intensity during the week. Logistic regression analyses indicated that ergonomic stressors were a risk factor for all symptomatic groups (OR = 1.02 per point increase; 95% CI: 1.0-1.1). Time pressure (OR = 1.2 per point increase; 95% CI: 1.0-1.4) was also a significant risk factor for all symptomatic groups, while cognitive processing placed workers at higher risks for concurrent LB and UE symptoms (OR = 1.2; 95% CI: 1.0-1.4). Interpersonal demands placed individuals at a lower risk for LB symptoms (OR = 0.8; 95% CI: 0.5-1.0). Findings highlight the importance of intervention approaches that address time pressure, cognitive processing factors, and interpersonal demands at work. In light of past biobehavioral studies, these results also suggest that job redesign and interventions that address a worker's workstyle when faced with increased work demands may help reduce the likelihood of musculoskeletal symptoms and/or their intensity.     

Job exposures as correlates of recovery in population-based rehabilitation intervention for work-related low back disorders

PURPOSE: Evaluating the impact of population-based rehabilitation interventions for work-related low back disorders (WR-LBD) requires job exposure factors to be considered as time-varying covariates. The role of job factors in recovery has not been well-established as most studies are based upon clinic samples, not working populations. This report represents the initial exploration of variables to be included in modeling job exposures as time-varying covariates of a study of work-place based rehabilitation intervention.METHODS: The study sample consisted of 162 hourly production employees from two automotive plants with work-related low back disorder not due to external trauma. Data reported herein were collected at baseline from an on-going large randomized clinical trial of rehabilitation for WR-LBD. Low back pain as measured by the North American Spine Society Baseline Form was examined in relation to: self-reported job factors from the Job Content Questionnaire and job risk category for low back disorder determined by the Lumbar Motion Monitor (LMM), an electronic goniometer which transmits back motion signals to a computer for analysis.RESULTS: Low back pain, with and without leg pain, was not found to be associated with hours worked in the previous week, job shift, perceptions of the pace of the job, or job risk of low back disorder as measured by the LMM. Low back pain was significantly (p < 0.05) correlated with perceptions of: how hard the work was, how much physical effort was required, how hectic the job was, whether or not there was sufficient time to do the job, and how much concentration and physical effort were required for the job.CONCLUSIONS: Self-report of perceptions of job strain may be as important, if not more important, than current quantitative factors thought to influence recovery from work-related low back pain.     

Physical workload, work intensification, and prevalence of pain in low wage workers: results from a participatory research project with hotel room cleaners in Las Vegas

BACKGROUND: Occupational injury rates among hotel workers exceed the national service sector average. This study assesses the prevalence of back and neck pain, and its associations with physical workload, ergonomic problems, and increasing work demands. METHODS: Nine hundred forty-one unionized hotel room cleaners completed a survey about health and working conditions. Associations between job demands and pain were determined by logistic regression models adjusting for individual characteristics, cumulative work demands, care-taking responsibilities at home, and psychosocial job factors. RESULTS: The 1-month prevalence of severe bodily pain was 47% in general, 43% for neck, 59% for upper back, and 63% for low back pain. Workers in the highest exposure quartiles for physical workload and ergonomic problems were between 3.24 and 5.42 times more likely to report severe pain than workers in the lowest quartile. Adjusted odds ratios for work intensification ranged from 1.74 (upper back) to 2.33 (neck). CONCLUSIONS: Most room cleaners experience severe back or neck pain. Severe pain showed strong associations with physical workload, work intensification, and ergonomic problems.     

Job strain, iso-strain, and the incidence of low back and neck injuries. A 7.5-year prospective study of San Francisco transit operators

Work-related musculoskeletal disorders account for the largest single category of lost-time occupational injury or disease episodes in industrialized countries. In this study we analyzed the impact of the psychosocial work environment, conceptualized by the demand-control-support model, on the incidence of low back and neck injury in a cohort of 1221 public transit operators followed for 7 years and 6 months. The two main exposure variables were "job strain" (mismatch of high psychological demands and low decision latitude) and "iso-strain" (job strain plus exposure to low social support at work). Analyses controlled for demographic factors, physical workload, and pain at baseline. For low back injuries, increased hazard rates were found for job strain and iso-strain based on tertiles, with hazard ratios (HR) of 1.30 (95% CI=0.96-1.75) and 1.41 (95% CI=0.98-2.01), respectively. Job strain and iso-strain based on median split or analyzed as continuous variables were not associated with low back injuries. For neck injuries, job strain and iso-strain based on median split showed HRs of 1.27 (95% CI=0.99-1.63) and 1.33 (95% CI=1.01-1.77), respectively. Job strain and iso-strain based on tertiles had HRs of 1.52 (95% CI=1.13-2.05) and 1.73 (95% CI=1.21-2.45), respectively. When analyzed as continuous variables, a one-point increase on the job strain and iso-strain scales led to an 8% (95% CI=0.98-1.19) and 14% (95% CI=1.02-1.27) increased hazard of neck injuries, respectively. This study shows the importance of the psychosocial work environment in the etiology of musculoskeletal injuries among transit operators. Since reviews have shown that psychosocial workplace conditions in this occupational group can be changed, these findings indicate a potential for prevention at the workplace.     

External validation of psychological job demands in a bus driver sample

Psychosocial risk factors have been considered as characteristics of the work environment rather than an individual issue, but their presence in the workplace is usually measured by self-reported questionnaires, based on worker attitudes. The objective of the study was to compare a self-reported measure of psychological job demands in a bus driver sample with selected indicators of bus company activity, as external 'objective' indicators, in order to assess its external validity. The final sample included 713 drivers in 41 routes. Self-reported measures of psychosocial work risk factors were obtained by the Job Content Questionnaire (JCQ). Four external indicators were available for each route: passengers, break times, bus incidents, and regulating actions. Spearman's correlation coefficient was estimated to assess the validity. Correlation coefficients showed that self-reported psychological demands were statistically significant correlated (p<0.05) with two external indicators: bus incidents (rho=0.397), and regulating actions (rho=0.475). Self-reported psychosocial risk factors have been compared with independent external indicators of the psychosocial work environment, trying to avoid any subject's perception. According to our results, psychological demands measured by the JCQ seem to reflect the actual psychosocial work environment. Other studies are necessary to confirm these results and to assess job control and job social support. This would be another step in improving our knowledge of the quality of measurement of psychosocial risk factors.