title: Causal assessment of occupational sitting and low back pain: results of a systematic review.
abstract: BACKGROUND
  Low back pain (LBP) is a common and disabling musculoskeletal disorder that often occurs in a working-age population. Determining the precise causation of LBP remains difficult. Any attempt to implicate a specific occupational activity in the genesis of LBP requires a methodologically rigorous approach.
  
  
  OBJECTIVE
  To conduct a systematic review of the scientific literature focused on evaluating the causal relationship between occupational sitting and LBP.
  
  
  METHODS
  Systematic review of the literature using Medline, EMBASE, CINAHL, Cochrane Library, Occupational Safety and Health database, grey literature, hand-searching occupational health journals, reference lists of included studies, and content experts. Evaluation of study quality using a modified version of the Newcastle-Ottawa Scale. Summary levels of evidence supporting Bradford-Hill criteria for different categories of sitting and types of LBP.
  
  
  METHODS
  Studies reporting an association between occupational sitting and LBP.
  
  
  METHODS
  Numerical association between different levels of exposure to occupational sitting and the presence or severity of LBP.
  
  
  METHODS
  A systematic review was performed to identify, evaluate, and summarize the literature related to establishing a causal relationship, according to Bradford-Hill criteria, between occupational sitting and LBP.
  
  
  RESULTS
  This search yielded 2,766 citations. Twenty-four studies met the inclusion/exclusion criteria and five were high-quality studies, including two case-controls and three prospective cohorts. Strong, consistent evidence was found for no association between occupational sitting and LBP. A moderate level of evidence was found for the absence of any dose-response trend. Risk estimates evaluating temporality were not statistically significant. Biological plausibility was not discussed in these studies. No evidence was available to assess the experiment criterion.
  
  
  CONCLUSIONS
  This review failed to uncover high-quality studies to support any of the Bradford-Hill criteria to establish causality between occupational sitting and LBP. Strong and consistent evidence did not support criteria for association, temporality, and dose response. Based on these results, it is unlikely that occupational sitting is independently causative of LBP in the populations of workers studied.
authors.affiliation: Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Darren M
authors.initials: DM
authors.lastname: Roffey
authors.forename: Eugene K
authors.initials: EK
authors.lastname: Wai
authors.forename: Paul
authors.initials: P
authors.lastname: Bishop
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kwon
authors.forename: Simon
authors.initials: S
authors.lastname: Dagenais
mesh_terms: D016206:Databases, Bibliographic; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D009784:Occupational Diseases / Q000209:etiology* / Q000503:physiopathology; D016273:Occupational Exposure / Q000009:adverse effects*; D011187:Posture / Q000502:physiology*