title: Development and validation of a job exposure matrix for physical risk factors in low back pain.
abstract: OBJECTIVE
  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).
  
  
  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.
authors.affiliation: Centre of Expertise for Health and Work Ability, Finnish Institute of Occupational Health, Helsinki, Finland. svetlana.solovieva@ttl.fi
authors.forename: Svetlana
authors.initials: S
authors.lastname: Solovieva
authors.forename: Irmeli
authors.initials: I
authors.lastname: Pehkonen
authors.forename: Johanna
authors.initials: J
authors.lastname: Kausto
authors.forename: Helena
authors.initials: H
authors.lastname: Miranda
authors.forename: Rahman
authors.initials: R
authors.lastname: Shiri
authors.forename: Timo
authors.initials: T
authors.lastname: Kauppinen
authors.forename: Markku
authors.initials: M
authors.lastname: Heliövaara
authors.forename: Alex
authors.initials: A
authors.lastname: Burdorf
authors.forename: Kirsti
authors.initials: K
authors.lastname: Husgafvel-Pursiainen
authors.forename: Eira
authors.initials: E
authors.lastname: Viikari-Juntura
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006306:Health Surveys; D006801:Humans; D017116:Low Back Pain / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult