Developing common metrics of mechanical exposures across aetiological studies of low back pain in working populations for use in meta-analysis.

OBJECTIVES: One of the challenges of conducting meta-analyses on the relationship between workplace mechanical exposures and low back pain is that mechanical exposures are reported in a wide variety of ways. We aimed to develop common metrics to apply in the translation of literature-based workplace mechanical exposures for use in meta-analyses, and to test the metrics' measurement properties. METHODS: We developed a set of 7-point scales to capture the intensity of important aspects of mechanical exposures that may be related to the development of low back pain in workers. The scales represented three dimensions of mechanical exposures at work: (1) trunk posture, (2) weight lifted or force exerted and (3) spinal loading, and estimated both peak and cumulative loads. Measurement properties of the scales were tested through a survey of experts in biomechanics and ergonomics who were asked to rate literature-based workplace exposure definitions using the scales and provide estimates of their confidence in their ratings. RESULTS: For each dimension the ratings for peak loads tended to be higher than the cumulative load ratings. The inter-rater reliability for the scales ranged from 0.3 to 0.5; we would need to average the ratings of at least four expert raters to have an acceptable level of reliability (>0.7). Inter-expert reliability was positively related to the experts' level of confidence in their ratings. In most cases the ranking of intensity ratings from the experts matched the ranking of exposure intensity from the original articles. CONCLUSIONS: This study provides insight into estimating the intensity of literature-based mechanical exposure metrics using a common set of scales which can be applied across epidemiologic studies. These metrics may be useful to quantify the relationship between workplace mechanical exposure and low back pain in a systematic review and meta-analysis.

Healthcare use before and after a workplace injury in British Columbia, Canada.

OBJECTIVES: There is growing evidence that occupational injuries influence workers' emotional and physical wellbeing, extending healthcare use beyond what is covered by the Workers' Compensation Board (WCB). METHODS: The authors used an administrative database that links individual publicly funded healthcare and WCB data for the population of British Columbia (BC), Canada. They examined change in service use, relative to one year before the injury, for workers who required time off for their injuries (lost time = LT) and compared them to other injured workers (no lost time = NLT) and individuals in the population who were not injured (non-injured = NI). RESULTS: LT workers increased physician visits (22%), hospital days (50%), and mental healthcare use (43% physician visits; and 70% hospital days) five years after the injury, relative to the year before the injury, at a higher rate than the NI group. For the NLT workers, the level of increased use following the injury was between that of these two groups. These patterns persisted when adjusting for registration in the BC Medical Service Plan (MSP) and several workplace characteristics. CONCLUSIONS: Although the WCB system is the primary mechanism for processing claims and providing information about workplace injury, it is clear that the consequences of workplace injury extend beyond what is covered by the WCB into the publicly funded healthcare system.

How low can they go? Potential for reduction in work injury rates.

BACKGROUND: There is a considerable variability in occupational injury rates across companies, even within the same industry. The aim of this study was to estimate how many injuries could be prevented if all firms could achieve the performance of their better peers. METHOD: Data were obtained from the Workplace Safety & Insurance Board of Ontario on all insured firms in the province. Within rate groups (firms in the same type of business) the number of injuries expected if all firms had a lost time injury rate at the 25th percentile of the distribution for the rate group were estimated. The total number of injuries were compared with the expected number, after adjusting for firm size and type of injury. RESULTS: Overall, using the 25th percentile as a benchmark, 42% of lost time injuries in Ontario could be prevented. DISCUSSION: There is considerable potential for prevention of work injuries based on currently achieved, non-optimal benchmarks.

How much science is there in injury prevention and control?

OBJECTIVES: To determine what proportion of research papers at an injury prevention conference reported an evaluation. METHODS: A random sample of 250 abstracts from the 6th World Conference on Injury Prevention and Control were classified by methodological type. Those that described any evaluation were further subdivided by whether the evaluation was of process or if it used an intermediate or "true" outcome. RESULTS: Of 250 abstracts, 20 (8%; 95% confidence interval 5.0% to 12.1%) showed evaluations with intermediate or true outcomes. Research designs were weak. Among the 20 reports, none was a randomized trial and only two conducted a before and after study with control group. The remaining 17 used before-after or "after only" designs. CONCLUSION: The conference papers included few evaluations. To ensure that resources are best used, those in the injury prevention field must increase their use of rigorous evaluation.

Work correlates of back problems and activity restriction due to musculoskeletal disorders in the Canadian national population health survey (NPHS) 1994-5 data.

OBJECTIVES: To describe the prevalence of musculoskeletal problems in the Canadian working population and to determine cross sectional associations between such problems and work factors, particularly job strain and physical demand variables. METHODS: The Canadian 1994 national population health survey (NPHS) sampled 4230 working men and 4043 working women (ages 18-64) who answered an abbreviated version of the job content questionnaire. Workers were classified into four strain categories: high, passive, active, and low. Outcomes were restricted activity due to musculoskeletal disorders and the diagnosis of a back problem (both yes or no). Survey weights were incorporated to allow for different probabilities of selection. Logistic regression analyses were carried out separately for women and men, controlling for sociodemographic factors. RESULTS: Prevalence of chronic back problems diagnosed by a health practitioner was 14.5% among men and 12.5% among women. Men had a 6.6% prevalence of restricted activity due to musculoskeletal disorders, whereas the corresponding figure for women was 5.3%. Women, but not men, in high strain jobs were more likely to report both back problems (odds ratio (OR) 1.60, 95% confidence interval (95% CI) 1.14 to 2.28) and restricted activity (OR 1.98, 95% CI 1.16 to 3.48) compared with those in low strain jobs. High physical exertion was an independent predictor of back problems in both sexes. For both men and women, low social support at work and high job insecurity were independent predictors of restricted activity due to musculoskeletal disorders. Conversely, chronic back problems contributed to explanation of high job strain among women (OR 1.76, 95% CI 1.30 to 2.39) and high physical exertion among men (OR 1.39, 95% CI 1.09 to 1.77), whereas restricted activity due to musculoskeletal disorders contributed to explanation of high job insecurity in both sexes. CONCLUSIONS: Associations of interest between work stressors and musculoskeletal problems in this cross sectional study provide evidence for physical and psychosocial factors both affecting disability and being affected by disability in a working population.

Creating safer and healthier workplaces: role of organizational factors and job characteristics.

BACKGROUND: A comprehensive understanding of workplace organizational risk factors for illness and injury and interventions to alleviate these factors is important for workplace prevention efforts. METHODS: We summarize the evidence for the role of workplace organizational factors and work factors in occupational health and safety (OHS). To the extent possible, we concentrate on factors at the level of the workplace, rather than the level of the individual. RESULTS: Three types of outcomes are considered: injuries, ill-health, and musculoskeletal problems; and we note the evidence for their relationship to work. We review workplace interventions intended to alleviate each type of outcome and note methodological limitations of previous research. CONCLUSIONS: Despite the methodological limitations, the balance of the literature supports the work-relatedness of the three types of outcomes, although questions remain about exact mechanisms and the effectiveness of specific interventions. We discuss barriers to and incentives for creating safer and healthier workplaces.

Job strain and self-reported health among working women and men: an analysis of the 1994/5 Canadian National Population Health Survey.

This paper explores the associations, for working women and men, of high strain jobs with self-rated health in the 1994/95 Canadian National Population Health Survey (NPHS). NPHS data were obtained on men (n = 4230) and women (n = 4043), aged 18-64 who answered an abbreviated version oF the job content questionnaire (JCQ). Using the upper and lower tertiles of psychological demands and decision latitude as cut points we classified workers into high strain and other jobs. Self-rated health was the outcome. We used polytomous logistic regression analyses and controlled for potential personal and home confounders; two risk parameters were estimated: for the odds of reporting poor/fair and good health both vs. very good/excellent health. High strain work was reported by 11% of women and 9% of men. After adjusting for potential confounders, high job strain was consistently associated with worse self-rated health in both models for each gender.

Biomechanical and psychosocial risk factors for low back pain at work.

OBJECTIVES: This study determined whether the physical and psychosocial demands of work are associated with low back pain. METHODS: A case-control approach was used. Case subjects (n = 137) reported a new episode of low back pain to their employer, a large automobile manufacturing complex. Control subjects were randomly selected from the study base as cases accrued (n = 179) or were matched to cases by exact job (n = 65). Individual, clinical, and psychosocial variables were assessed by interview. Physical demands were assessed with direct workplace measurements of subjects at their usual jobs. The analysis used multiple logistic regression adjusted for individual characteristics. RESULTS: Self-reported risk factors included a physically demanding job, a poor workplace social environment, inconsistency between job and education level, better job satisfaction, and better coworker support. Low job control showed a borderline association. Physical-measure risk factors included peak lumbar shear force, peak load handled, and cumulative lumbar disc compression. Low body mass index and prior low back pain compensation claims were the only significant individual characteristics. CONCLUSIONS: This study identified specific physical and psychosocial demands of work as independent risk factors for low back pain.

Changes in general health and musculoskeletal outcomes in the workforce of a hospital undergoing rapid change: a longitudinal study.

This article aimed to examine changes in general health and time with back pain and neck pain and to identify predictors of any such changes. Hospital workers were studied longitudinally with surveys in 1995, 1996, and 1997 (N = 712). Back and neck pain were reported only at the 2nd and 3rd surveys. There was a significant decline in general health and significant increases in time with neck pain and back pain. Predictors of changes in these outcomes were mainly work-related variables (initial or change values), such as job interference with family, job influence, work psychological demands, and hours worked.

Predictors of job stress and satisfaction among hospital workers during re-engineering: differences by extent of supervisory responsibilities.

After two years of rapid organizational change within a large teaching hospital, 83 percent of workers remained employed there. Among these "survivors," job satisfaction decreased and job stress increased regardless of whether they were employed in a supervisory position. This article examines the predictors of job satisfaction and job stress for managers, for people who indicated that they supervised others but were not managers, and for workers. There are areas of commonality in predictors across these groups, as well as some differences by level of supervisory responsibility. Examining and modifying job characteristics associated with high stress could result in healthier hospital work environments.

Clinical effectiveness of pneumococcal vaccine. Meta-analysis.

OBJECTIVE: To determine the clinical effectiveness of pneumococcal vaccine. DATA SOURCES: Computerized searches of MEDLINE, EMBASE, and SCISEARCH databases were performed, reference lists of retrieved articles were reviewed, and first authors of published studies were contacted. STUDY SELECTION: Studies of use of pneumococcal vaccines in adults were included if the study design was a randomized or quasi-randomized controlled trial and at least one of the following clinical outcomes was reported: vaccine-type systemic pneumococcal infection, systemic pneumococcal infection, vaccine-type pneumococcal pneumonia, pneumococcal pneumonia, non-vaccine-type pneumococcal pneumonia. SYNTHESIS: Study quality was assessed and descriptive information concerning the study populations, interventions, and outcome measurements was extracted for 13 trials involving more than 65,000 patients. Estimates of vaccine efficacy, based on a meta-analysis of randomized and quasi-randomized trials, were determined for clinical outcomes. CONCLUSIONS: Vaccination with pneumococcal polysaccharide vaccine can be expected to reduce the risk of systemic infection due to pneumococcal types included in the vaccine by 83% and systemic infection due to all pneumococci by 73%. We found no evidence that the vaccine was less efficacious for the elderly, institutionalized people, or those with chronic disease.

Comparison of four peak spinal loading exposure measurement methods and their association with low-back pain.

OBJECTIVES: This paper examines the performance of 4 different methods of estimating peak spinal loading and their relationship with the reporting of low-back pain. METHODS: The data used for this comparison was a subset of subjects from a case-referent study of low-back-pain reporting in the automotive industry, in which 130 random referents and 105 cases (or job-matched proxies) were studied. The peak load on the lumbar spine was determined using a biomechanical model with model inputs coming from a detailed self-report questionnaire, a task-based check list, a video digitization method, and a posture and load sampling technique. RESULTS: The methods were directly comparable through a common metric of newtons or newton meters of spinal loading in compression, shear, or moment modes. All the methods showed significant and substantial associations with low-back pain in all modes (odds ratios 1.6-2.3). The intraclass correlation coefficients (ICC) showed strong similarities between the checklist and video digitized techniques (ICC 0.84-0.91), moderate similarities between these techniques and the work sampling method (ICC 0.49-0.52), and poor correlations (ICC 0.16-0.40) between the self-report questionnaire and the observer recorded measures. CONCLUSIONS: While all the methods detected significant odds ratios, they cannot all be used interchangeably for risk assessment at the individual level. Peak spinal compression, moment, and shear are important risk factors for low-back pain reporting, no matter which measurement method is used. Questionnaires can be used for large-scale studies. At the individual level a task-based checklist provides biomechanical model inputs at lower cost and equal performance compared with the criterion video digitization system.

Determinants of job stress and job satisfaction among supervisory and non-supervisory employees in a large Canadian teaching hospital.

This article explores the extent to which hospital workers at a large teaching hospital at different managerial/supervisory levels (designated and non-designated supervisors, and non-supervisory staff), experienced job stress and job satisfaction prior to the re-engineering of hospital services. For all groups, increased levels of job demands were associated with higher levels of stress. Lower levels of decision latitude were associated with increased job stress for designated supervisors. Increasing levels of decision latitude were associated with both job stress and satisfaction for the other two groups. Co-worker support and teamwork contributed to increased job satisfaction for all groups.

The impact of re-engineering and other cost reduction strategies on the staff of a large teaching hospital: a longitudinal study.

OBJECTIVES: To examine changes over time in the hospital staff's perceptions of how rapid organizational change, caused by fiscal constraints imposed by governments, affects them, their work environment, and the quality of care and services that they provide. METHODS: A random sample of hospital employees (n = 900) of a large Ontario teaching hospital participated in a longitudinal study which involved surveys at 3 measurement periods over a 2-year period. The questionnaire used in this study included scales reflecting work environment, emotional distress, personal resources, spillover from work to home and vice versa, and perceptions regarding patient care and the hospital as an employer. RESULTS: Significant increases in depression, anxiety, emotional exhaustion, and job insecurity were seen among employees, particularly during the first year of the change process. By the end of the second year, employees reported deterioration in team work, increased unclarity of role, and increased use of distraction to cope. Job demands increased throughout the period whereas little change occurred in the employee's job influence or decision latitude. Overall, the work environment was negatively affected. Although patient care was unaffected in the first year, a significant decline in perceptions of patient care, attention to quality improvement, and overall quality of care were later seen. CONCLUSIONS: This study raises questions about whether hospital re-engineering and mergers will be able to achieve the cost reductions sought without sacrificing quality of work life. Along with the rapid change, there was increase in emotional distress among staff and a deterioration in their relationship with their employer.

Upper limb work-related musculoskeletal disorders among newspaper employees: cross-sectional survey results.

At a metropolitan newspaper office in Canada with extensive video display terminal (VDT) use, researchers carried out a survey (n = 1,007, 84% response) to establish baseline prevalence of work-related musculoskeletal disorders (WMSDs) and to identify demographic, postural, task, and psychosocial factors associated with WMSD symptoms. One-fifth of the respondents reported moderate or worse upper limb pain recurring at least monthly or lasting more than a week over the previous year. Logistic regression showed that employees who faced frequent deadlines and high psychological demands (fast work pace and conflicting demands), had low skill discretion and social support, spent more time keyboarding, or who had their screen in a non-optimal position were more likely to report moderate to severe symptoms. Women reported significantly higher levels of symptoms than men.

Disability resulting from occupational low back pain. Part I: What do we know about primary prevention? A review of the scientific evidence on prevention before disability begins.

This is the first of two papers that systematically review available scientific evidence on the causes of disability from occupational low back pain, and the effectiveness of interventions to prevent it-before disability begins (primary prevention-Part I) and after its onset (secondary prevention-Part II). This first paper reviews the risk factors for the onset of pain and associated disability followed by a critical summary of intervention studies attempting to achieve prevention and to evaluate the results.

Disability resulting from occupational low back pain. Part II: What do we know about secondary prevention? A review of the scientific evidence on prevention after disability begins.

This is the second of two papers that systematically review available scientific evidence on the causes of disability from occupational low back pain, and the effectiveness of interventions to prevent it after its onset (secondary prevention). This paper reviews the national history of how back pain and the risk factors for its extension into chronic disability, followed by a critical summary of intervention studies attempting to reduce the duration of this disability, and to evaluate the results.

Long-term back problems and physical work exposures in the 1990 Ontario Health Survey.

OBJECTIVES: This study sought to provide data on the relationship of work exposures to long-term back problems in a population survey. METHODS: The Ontario Health Survey in 1990 used a representative population sample of the province. It included data on long-term back problems, occupational activity, and physical work exposures. The current study examined relationships between these variables. RESULTS: The prevalence of long-term back problems was 7.8% in working-age adults. It generally increased with age. Long-term back problems were more prevalent in blue-collar occupations and among those not working, as well as among people with less formal education, smokers, and those overweight. Physical work exposures--awkward working position, working with vibrating vehicles or equipment, and bending and lifting--were all associated with a greater risk of back problems. The number of simultaneous physical exposures was monotonically related to increased risk. CONCLUSIONS: Within the limitations of the data and assuming the relationship to be causal, about one quarter of the excess back pain morbidity in the working population could be explained by physical work exposures.

Workplace organizational correlates of lost-time accident rates in manufacturing.

We report the results of a questionnaire survey of manufacturing workplaces related to the lost-time frequency rates (LTFR) for Workers' Compensation claims. Six types of industry were chosen.' metal articles, plastic articles, grain products, textile manufacturing, printing, and automobile manufacturing. LTFR were standardized by type of industry. Stratifying simultaneously by number of employees and LTFR category, we sampled 718 workplaces. A mail questionnaire to labor and management representatives provided at least some information on 58%. Response rates were similar across LTFR categories, and telephone interviews of non-responders showed little difference in their replies from those obtained in completed questionnaires. A large number of variables were examined. Apart from statistical significance, we looked for consistency in trends across LTFR categories and in patterns for similar questions. Significant associations grouped into several areas. Lower LTFR were associated with: concrete demonstration by management of its concern for the workforce; greater involvement of workers in general decision-making; greater willingness of the Joint Health and Safety Committee to solve problems internally; and greater experience of the workforce. Variables that were not significant included profitability and financial performance. A final stepwise multiple regression explained 19% of the variance in LTFR, although this analysis suffered from several limitations.

Using Labour Force Survey and census data to generate denominators for occupational injury rates: an application and expansion of Haggar-Guénette's method.

The calculation of rates of occupational injury claims is essential to identify groups at high risk, yet limitations of denominator data have often restricted our capacity to do this. Haggar-Guénette's method of using Statistics Canada's data on paid workers from the Labour Force Survey as denominators has been expanded by incorporating information from the Census. The method is illustrated by calculating denominators for male construction industry workers within the province of Ontario. Information for paid workers employed in construction occupations was derived from the Labour Force Survey to produce denominators for those aged 15-64, overall and by 10-year age groups. Census data on the distribution of construction occupational roles were applied to produce denominators both overall, then simultaneously by age and by occupational role. Advantages and disadvantages, including the limitations or biases due to the differing sources for denominators and numerators are identified.