Development and validation of a job exposure matrix for physical risk factors in low back pain

PLoS One. 2012;7(11):e48680. doi: 10.1371/journal.pone.0048680. Epub 2012 Nov 12.

Abstract

Objectives: The aim was to construct and validate a gender-specific job exposure matrix (JEM) for physical exposures to be used in epidemiological studies of low back pain (LBP).

Materials and methods: We utilized two large Finnish population surveys, one to construct the JEM and another to test matrix validity. The exposure axis of the matrix included exposures relevant to LBP (heavy physical work, heavy lifting, awkward trunk posture and whole body vibration) and exposures that increase the biomechanical load on the low back (arm elevation) or those that in combination with other known risk factors could be related to LBP (kneeling or squatting). Job titles with similar work tasks and exposures were grouped. Exposure information was based on face-to-face interviews. Validity of the matrix was explored by comparing the JEM (group-based) binary measures with individual-based measures. The predictive validity of the matrix against LBP was evaluated by comparing the associations of the group-based (JEM) exposures with those of individual-based exposures.

Results: The matrix includes 348 job titles, representing 81% of all Finnish job titles in the early 2000s. The specificity of the constructed matrix was good, especially in women. The validity measured with kappa-statistic ranged from good to poor, being fair for most exposures. In men, all group-based (JEM) exposures were statistically significantly associated with one-month prevalence of LBP. In women, four out of six group-based exposures showed an association with LBP.

Conclusions: The gender-specific JEM for physical exposures showed relatively high specificity without compromising sensitivity. The matrix can therefore be considered as a valid instrument for exposure assessment in large-scale epidemiological studies, when more precise but more labour-intensive methods are not feasible. Although the matrix was based on Finnish data we foresee that it could be applicable, with some modifications, in other countries with a similar level of technology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Female
  • Health Surveys
  • Humans
  • Low Back Pain / epidemiology*
  • Low Back Pain / etiology*
  • Male
  • Middle Aged
  • Occupational Exposure*
  • Prevalence
  • Reproducibility of Results
  • Risk Factors
  • Sex Factors
  • Young Adult

Grant support

This study was funded by the Finnish Work Environment Fund (project number 109364) and Academy of Finland (project number 129364). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.