Objective: Work-related musculoskeletal disorders (MSDs) are the leading cause of work disability in the developed economies. The objective of this study was to describe trends in the incidence of MSDs attributed to work exposures in Ontario over the period 2004–2011.
Methods: An observational study of work-related morbidity obtained from three independent sources for a complete population of approximately six million occupationally active adults aged 15–64 in the largest Canadian province. We implemented a conceptually concordant case definition for work-related non-traumatic MSDs in three population-based data sources: emergency department encounter records, lost-time workers' compensation claims and representative samples of Ontario workers participating in consecutive waves of a national health interview survey.
Results: Over the 8-year observation period, the annual per cent change (APC) in the incidence of work-related MSDs was −3.4% (95% CI −4.9% to −1.9%) in emergency departments' administrative records, −7.2% (−8.5% to −5.8%) in lost-time workers' compensation claims and −5.3% (−7.2% to −3.5%) among participants in the national health interview survey. Corresponding APC measures for all other work-related conditions were −5.4% (−6.6% to −4.2%), −6.0% (−6.7% to −5.3%) and −5.3% (−7.8% to −2.8%), respectively. Incidence rate declines were substantial in the economic recession following the 2008 global financial crisis.
Conclusions: The three independent population-based data sources used in this study documented an important reduction in the incidence of work-related morbidity attributed to non-traumatic MSDs. The results of this study are consistent with an interpretation that the burden of non-traumatic MSDs arising from work exposures is declining among working-age adults.
Source: Cameron A Mustard, Andrea Chambers, Selahadin Ibrahim, Jacob Etches, Peter Smith. Occup Environ Med, 2014.
Objectives: Physical exposures (eg, lifting or bending) are believed to be risk factors for low-back pain (LBP), but the literature is inconsistent. Exposure and LBP prevalence differ considerably between occupations, and exposure–outcome associations could be severely modified by the presence of particular occupational groups. We aimed to investigate the influence of such outlying groups on the properties of associations between exposure and LBP.
Methods: Lifting and trunk flexion were observed for 371 of 1131 workers within 19 groups. LBP was obtained from all workers during three follow-up years. Both exposure variables were associated with LBP (P<0.01) in this parent dataset. By removing the 19 groups one-by-one and performing logistic regressions analysis on the 18 remaining groups, we demonstrated that one group, mainly road workers, with outlying exposures and LBP prevalence substantially affected the exposure–outcome association in the total population. In order to further examine this phenomenon, we assessed, by simulation, the influence of realistic sizes (n=4, 8, 16, 32, 64, 128), mean exposures (e=2000, 3000, 4000 lifts and e=30, 40, 50% trunk flexion time) and LBP prevalences (p=70, 80, 90, 100%) of the outlying group on the strength and certainty of the eventual relationship between exposure and LBP. For each combination of n, e and p, 3000 virtual studies were constructed, including the simulated group together with the other 18 original groups from the parent data-set. Average odds ratios (OR), 95% confidence limits, and power (P<0.05) were calculated across these 3000 studies as measures of the properties of each virtual study design.
Results: OR were attenuated more towards 1 and power decreased with smaller values of n, e, and p in the outlying group. Changes in group size and prevalence had a larger influence on OR and power than changes in mean exposure.
Conclusions: The size and characteristics of a single group with high exposure and outcome prevalence can strongly influence both the OR point estimate and the likelihood of obtaining significant exposure–outcome associations in studies of large populations. These findings can guide interpretations of prior epidemiological studies and support informed design of future studies.
Source: Coenen P, Mathiassen SE, Kingma I, Boot CRL, Bongers PM, van Dieën JH. 2014, Scand J Work Environ Health.
Objective: The aim of this study was to evaluate the prevalence of upper-body-quadrant pain among ultrasonographers and to evaluate the association between individual ergonomics, musculoskeletal disorders, and occurrence of neck pain.
Method: A hundred and ten (N = 110) Belgian and Dutch male and female hospital ultrasonographers were consecutively enrolled in the study. Data on work-related ergonomic and musculoskeletal disorders were collected with an electronic inquiry, including questions regarding ergonomics (position of the screen, high-low table, and ergonomic chair), symptoms (neck pain, upper-limb pain), and work-related factors (consecutive working hours a day, average working hours a week).
Results: Subjects with the screen on their left had significantly more neck pain (odds ratio [OR] = 3.6, p = .0286). Depending on the workspace, high-low tables increased the chance of developing neck pain (OR = 12.9, p = .0246). A screen at eye level caused less neck pain (OR = .22, p = .0610). Employees with a fixed working space were less susceptible to arm pain (OR = 0.13, p = .0058). The prevalence of arm pain was significantly higher for the vascular department compared to radiology, urology, and gynecology departments (OR = 9.2, p = .0278).
Conclusions: Regarding prevention of upper-limb pain in ultrasonograph, more attention should be paid to the work environment and more specialty to the ultrasound workstation layout. Primary ergonomic prevention could provide a painless work situation for the ultrasonographer.
Application: Further research on the ergonomic conditions of ultrasonography is necessary to develop ergonomic solutions in the work environment that will help to alleviate neck and arm pain.
Source: Claes, Frank, Berger, Jan & Stassijns, Gäetane. Human Factors, 2014.
The objectives of this study were to develop a questionnaire that evaluates the perception of nursing workers to job factors that may contribute to musculoskeletal symptoms, and to evaluate its psychometric properties. Internationally recommended methodology was followed: construction of domains, items and the instrument as a whole, content validity, and pre-test. Psychometric properties were evaluated among 370 nursing workers. Construct validity was analyzed by the factorial analysis, known-groups technique, and convergent validity. Reliability was assessed through internal consistency and stability. Results indicated satisfactory fit indices during confirmatory factor analysis, significant difference (p < 0.01) between the responses of nursing and office workers, and moderate correlations between the new questionnaire and Numeric Pain Scale, SF-36 and WRFQ. Cronbach's alpha was close to 0.90 and ICC values ranged from 0.64 to 0.76. Therefore, results indicated that the new questionnaire had good psychometric properties for use in studies involving nursing workers.
Source: Orpinelli Coluci, Marina Zambon & Costa Alexandre, Neusa Maria. (2014). Applied Ergonomics, 45 (6), p. 1588-1596.
Pushing and pulling are potential risk factors for work-related low back disorders (WRLBDs). While several studies have evaluated differences in work methods related to work experience, such evidence for dynamic pushing and pulling is limited. Eight novices and eight experienced workers completed dynamic push/pull tasks using a cart weighted to 250% of individual body mass in two different configurations (preferred vs. elbow handle heights). Multiple measures [hand forces, torso kinematics and kinetics, and required coefficient of friction (RCOF)] were obtained to assess WRLBD and slip risks. Experienced workers generated higher medio-lateral hand forces, during both pulls and pushes, though with a more substantial difference during pushes (∼74%), and which involved the use of hand force components other than to move the cart in an anterior-posterior direction. Experienced workers also had lower peak torso kinematics in flexion/extension and lateral bending, and lower torso flexion/extension kinetics. The latter is suggestive of a lower risk for WRLBDs, though levels of exposures to WRLBD risk were low to moderate in both groups and were often relatively small and inconsistent across the task configurations. Group-level differences in RCOF were quite small, indicating a comparable slip risk between the two groups. Thus, it was considered inconclusive whether the work methods used by experienced workers during dynamic pushing and pulling are advantageous regarding WRLBD and slip risks.
Source: Lee, Jungyong, Nussbaum, Maury A., Kyung, Gyouhyung. (2014). International Journal of Industrial Ergonomics, 44(5), 647-653.
Natural experiment with 3-year follow-up
Objectives. This study investigated long-term effects and implementation processes of workplace strength training for musculoskeletal disorders. Methods. 333 and 140 laboratory technicians from private and public sector companies, respectively, replied to a 3-year follow-up questionnaire subsequent to a 1-year randomized controlled trial (RCT) with high-intensity strength training for prevention and treatment of neck, shoulder, and arm pain. Being a natural experiment, the two participating companies implemented and modified the initial training program in different ways during the subsequent 2 years after the RCT. Results. At 3-year follow-up the pain reduction in neck, shoulder, elbow, and wrist achieved during the first year was largely maintained at both companies. However, the private sector company was rated significantly better than the public sector company in (1) training adherence, (2) training culture, that is, relatively more employees trained at the workplace and with colleagues, (3) self-reported health changes, and (4) prevention of neck and wrist pain development among initially pain-free employees. Conclusions. This natural experiment shows that strength training can be implemented successfully at different companies during working hours on a long-term basis with lasting effects on pain in neck, shoulder, and arm.
Source: Mortensen P, Larsen AI, Zebis MK, et al. BioMed Research International, Volume 2014 (2014).
Utilisation des échelles de Borg
L'évaluation subjective est un outil précieux, précis et reproductible pour mesurer la charge de travail. Elle peut être utilisée seule(échelles d'auto-évaluation, questionnaires...) ou en parallèle aux nombreuses métrologies objectives.
Après une courte présentation de l'évaluation subjective à l'aide des échelles de Borg (RPE et CR10), des exemples d'études menées en laboratoire et en situation de travail sont présentés pour argumenter leurs utilisations et leurs apports dans un bilan des conditions de travail.
Source: J.P. Meyer. Références en santé au travail, septembre 2014, no 139, p. 105-122.
Results from a pooled data study of carpal tunnel syndrome
Objectives: This paper aimed to quantify exposure–response relationships between the American Conference of Governmental Industrial Hygienists' (ACGIH) threshold limit value (TLV) for hand-activity level (HAL) and incidence of carpal tunnel syndrome (CTS).
Methods: Manufacturing and service workers previously studied by six research institutions had their data combined and re-analyzed. CTS cases were defined by symptoms and abnormal nerve conduction. Hazard ratios (HR) were calculated using proportional hazards regression after adjusting for age, gender, body mass index, and CTS predisposing conditions.
Results: The longitudinal study comprised 2751 incident-eligible workers, followed prospectively for up to 6.4 years and contributing 6243 person-years of data. Associations were found between CTS and TLV for HAL both as a continuous variable [HR 1.32 per unit, 95% confidence interval (95% CI) 1.11–1.57] and when categorized using the ACGIH action limit (AL) and TLV. Those between the AL and TLV and above the TLV had HR of 1.7 (95% CI 1.2–2.5) and 1.5 (95% CI 1.0–2.1), respectively. As independent variables (in the same adjusted model) the HR for peak force (PF) and HAL were 1.14 per unit (95% CI 1.05–1.25), and 1.04 per unit (95% CI 0.93–1.15), respectively.
Conclusion: Those with exposures above the AL were at increased risk of CTS, but there was no further increase in risk for workers above the TLV. This suggests that the current AL may not be sufficiently protective of workers. Combinations of PF and HAL are useful for predicting risk of CTS.
Source: Kapellusch JM, Gerr FE, Malloy EJ, Garg A, Harris-Adamson C, Bao SS, Burt SE, Dale AM, Ellen E, Evanoff BA, Hegmann KT, Silverstein BA, Theise MS, Rempel DR. Scand J Work Environ Health, 2014.
Objective: To investigate a biopsychosocial model of risk for carpal tunnel syndrome (CTS). In addition, a host of exploratory psychosocial variables was investigated as potential risk factors for CTS.
Methods: A case–control design was used comparing 87 CTS and 74 sex-matched general orthopedic patients from an outpatient orthopedic clinic. All participants underwent the same diagnostic protocol (ie, physical evaluation and electrodiagnostic testing) and completed a self-report questionnaire assessing a wide range of potential occupational, personological, and psychosocial risk factors.
Results: Multiple logistic regression analyses revealed that occupational repetition, not engaging in vigorous exercise, physical activities with wrist strain, poorer physical health, and lower job satisfaction were significantly related to the presence of CTS. Obesity was borderline significantly related to the presence of CTS.
Conclusions: The biopsychosocial model provides a useful heuristic for conceptualizing CTS risk among injured workers.
Source: Goodson, Jason T.; DeBerard, M. Scott; Wheeler, Anthony J.; Colledge, Alan L. Journal of Occupational & Environmental Medicine: September 2014, Volume 56, Issue 9, p 965–972.
CBRG QuickDecks are now available from the Cochrane Back Review Group (CBRG), housed at the Institute for Work & Health. These slide decks provide a quick summary of the best evidence for treating back and neck pain by type of intervention, including surgical, pharmacological and non-pharmacological (e.g. massage, chiropractic) interventions.
Results From the Backworks Prospective Cohort Study
Objective: To evaluate relationships between lifting and lowering of loads and risk of low back pain resulting in medication use (M-LBP).
Methods: At baseline, worker demographics, psychosocial factors, hobbies, LBP history, and lifting and lowering (quantified using the Revised NIOSH Lifting Equation) were assessed. A cohort of 258 incident-eligible workers was followed up for 4.5 years to determine new M-LBP cases and changes in lifting/lowering requirements. Proportional hazards regression with time-varying covariates was used to model associations.
Results: Factors predicting M-LBP included peak lifting index (PLI) and composite lifting index (PCLI), LBP history, anxiety, and housework. In adjusted models, PLI and PCLI showed exposure–response relationships with peak hazard ratios of 3.8 and 4.3, respectively (P ≤ 0.02).
Conclusions: Lifting of loads is associated with increased risk of M-LBP. The PLI and PCLI are useful metrics for estimating the risk of M-LBP from lifting.
Source: Kapellusch, Jay M.; Garg, Arun; Boda, Sruthi; Hegmann, Kurt T.; Moore, J. Steven; Thiese, Matthew S.; Merryweather, Andrew; Tomich, Suzanna; Foster, James C.; Bloswick, Donald; Malloy, Elizabeth J. Journal of Occupational & Environmental Medicine: August 2014, Volume 56, Issue 8, p. 867–877.
Objective: We evaluated post-offer pre-placement (POPP) nerve conduction studies (NCS) for carpal tunnel syndrome (CTS), testing diagnostic yield and cost-effectiveness.
Methods: A total of 1027 newly hired workers underwent baseline NCS and were followed for an average of 3.7 years for diagnosed CTS. Measures of diagnostic yield included sensitivity, specificity, and positive predictive value (PPV). Cost-effectiveness of POPP screening was evaluated using a range of inputs.
Results: Abnormal NCS was strongly associated with future CTS with univariate hazard ratios ranging from 2.95 to 11.25, depending on test parameters used. Nevertheless, PPV was poor, 6.4% to 18.5%. Cost-effectiveness of POPP varied with CTS case costs, screening costs, and NCS thresholds.
Conclusions: Although abnormal NCS at hire increases risk of future CTS, the PPV is low, and POPP screening is not cost-effective to employers in most scenarios tested.
Source: Dale, Ann Marie; Gardner, Bethany T.; Zeringue, Angelique; Werner, Robert; Franzblau, Alfred; Evanoff, Bradley. Journal of Occupational & Environmental Medicine:
August 2014, Volume 56, Issue 8, p. 840–847.
This study of selected jobs in the health care sector explored a range of physical and psychosocial factors to identify those that most strongly predicted work-related musculoskeletal disorders (WMSD) risk. A self-report survey was used to collect data on physical and psychosocial risk factors from employees in three health care organisations in Victoria, Australia. Multivariate analyses demonstrated the importance of both psychosocial and physical hazards in predicting WMSD risk and provides evidence for risk management of WMSDs to incorporate a more comprehensive and integrated approach. Use of a risk management toolkit is recommended to address WMSD risk in the workplace.
Source: Oakman, Jodi, Macdonald, Wendy, Wells, Yvonne. (2014). Applied Ergonomics.
Review of Current Practice and Recommendations for Improvement
This document is a joint effort between NIOSH and the Canadian Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD).
The purpose of this document is to help practitioners assess working posture for the prevention and control of occupational musculoskeletal disorders (MSDs). Quantitative or semiquantitative descriptions of posture are inputs to many job analysis tools applied in MSD prevention and control. Studies of the relationship between risk factors (such as posture, repetition, and force) and resulting MSD prevalence have used various approaches to characterizing working posture, including observation-based methods. Posture classification by systematic observation of a worker is commonly used in research and by practitioners, such as ergonomists, industrial hygienists, and safety professionals, to help inform job design decisions and establish safe work limits to reduce MSD injury risk in the workplace.
A systematic review of observational studies
Systematically review observational studies concerning the question whether workers that perform pushing/pulling activities have an increased risk for upper extremity symptoms as compared to workers that perform no pushing/pulling activities. A search in MEDLINE via PubMed and EMBASE was performed with work-related search terms combined with push/pushing/pull/pulling. Studies had to examine exposure to pushing/pulling in relation to upper extremity symptoms. Two authors performed the literature selection and assessment of the risk of bias in the studies independently. A best evidence synthesis was used to draw conclusions in terms of strong, moderate or conflicting/insufficient evidence. The search resulted in 4764 studies. Seven studies were included, with three of them of low risk of bias, in total including 8279 participants. A positive significant relationship with upper extremity symptoms was observed in all four prospective cohort studies with effect sizes varying between 1.5 and 4.9. Two out of the three remaining studies also reported a positive association with upper extremity symptoms. In addition, significant positive associations with neck/shoulder symptoms were found in two prospective cohort studies with effect sizes of 1.5 and 1.6, and with shoulder symptoms in one of two cross-sectional studies with an effect size of 2.1. There is strong evidence that pushing/pulling is related to upper extremity symptoms, specifically for shoulder symptoms. There is insufficient or conflicting evidence that pushing/pulling is related to (combinations of) upper arm, elbow, forearm, wrist or hand symptoms.
Source: Hoozemans, Marco J.M., Knelange, E.B., Frings-Dresen, M.H.W., Veeger, H.E.J., et Kuijer, P.P.F.M. (2014). Occupational & Environmental Medicine.
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