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Translation of mechanical exposure in the workplace into common metrics for meta-analysis: a reliability and validity study
  1. Lauren E Griffith1,
  2. Richard P Wells2,
  3. Harry S Shannon1,3,
  4. Stephen D Walter1,
  5. Donald C Cole3,4,
  6. Pierre Côté4,5,
  7. John Frank4,6,
  8. Sheilah Hogg-Johnson3,
  9. Lacey E Langlois7 on behalf of the Meta-Analysis of Pain in the Lower Back and Work Exposures (MAPLE) Collaborative Group
  1. 1Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada
  2. 2Department of Kinesiology, University of Waterloo, Waterloo, Canada
  3. 3Institute for Work and Health, Toronto, Canada
  4. 4Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
  5. 5Center of Research Expertise in Improved Disability Outcomes (CREIDO), University Health Network, Toronto, Canada
  6. 6School of Clinical Science and Community Health, University of Edinburgh, UK
  7. 7Home and Continuing Care Development, Canadian Institute of Health Information, Ottawa, Canada
  1. Correspondence to Dr Lauren E Griffith, McMaster University, Department of Clinical Epidemiology and Biostatistics, DTC-314, 1280 Main Street West, Hamilton, Ontario, Canada, L8S 4L8; griffith{at}


Objectives We previously assessed inter-rater reliability of expert raters using six scales to estimate the intensity of literature-based mechanical exposures. The objectives of this study were to estimate the impact on the inter-rater reliability of using non-expert (NE) raters and to assess the validity of our scales.

Methods We used 7-point scales to represent three dimensions of mechanical exposures at work: 1) trunk posture, 2) weight lifted or force exerted and 3) spinal loading. We estimated both peak and cumulative loads and called this an “interpretive translation” of exposure. A second method, “algorithmic translation”, used the original units in which the exposure data was collected. These data were used to assess the inter-rater reliability and validity of the NE interpretive translation of exposure.

Results The NE inter-rater reliability for the scales ranged from 0.24 to 0.46. The correlation between the means of the NE and expert ratings were >0.7. Although there was a strong relationship between the NE interpretive and the algorithmic translation, there was some evidence that the interpretive translation plateaus at higher level of exposure.

Conclusions This study supports using NE raters to estimate the intensity of literature-based mechanical exposure metrics using a common set of scales which can be applied across epidemiologic studies. We would need to average the ratings of at least five NE raters to have an acceptable level of reliability (>0.7). These metrics may be useful to quantify the relationship between workplace mechanical exposure and low back pain in a systematic review and meta-analysis.

  • Biomechanics
  • low back pain
  • observer variation
  • meta-analysis
  • validity
  • epidemiology
  • ergonomics
  • back disorders
  • musculoskeletal
  • workload

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  • The MAPLE Collaborative Group are listed alphabetically in supplementary online appendix 1.

  • Funding This study was funded by the Canadian Institutes for Health Research (FRN-67042 and ICH-63069, part of the Interdisciplinary Capacity Enhancement (ICE) Teams Grant Program) and WorkSafeBC, with support from the Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD).

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the McMaster University Research Ethics Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.