BACKGROUND CONTEXT:Low back pain (LBP) is a prevalent and costly musculoskeletal
disorder that often occurs in the working-age population. Although numerous physical activities
have been implicated in its complex etiology, determining causation remains challenging and
requires a methodologically rigorous approach.
PURPOSE:To conduct a systematic review of the scientific literature focused on establishing
a causal relationship between awkward occupational postures and LBP.
STUDY DESIGN:Systematic review of the literature using MEDLINE, EMBASE, CINAHL,
Cochrane Library, and Occupational Safety and Health database, gray literature, hand-searching
occupational health journals, reference lists of included studies, and experts. Evaluation of method-ological quality using a modified Newcastle-Ottawa Scale for observational studies. Summary
levels of evidence for each of the Bradford Hill criteria for causality for each category of awkward
occupational posture and type of LBP.
SAMPLE:Studies reporting an association between awkward occupational postures and LBP.
OUTCOME MEASURES:Numerical association between different levels of exposure to
awkward occupational postures and the presence or severity of LBP.
METHODS:A systematic review was performed to identify, evaluate, and summarize the litera-ture related to establishing a causal relationship, according to Bradford Hill criteria, between
awkward occupational postures and LBP.
RESULTS:This search yielded 2,766 citations. Eight high-quality studies reported on awkward
occupational postures and LBP. Three were case-control studies, one was cross-sectional, and four
were prospective cohort studies. There was strong evidence for consistency of no association
between awkward occupational postures and LBP, with only two studies demonstrating significant
associations in most of their risk estimates compared with six studies reported mainly nonsignifi-cant associations. Two studies assessed dose response, with one study demonstrating a nonsignifi-cant dose-response trend. Three studies were able to assess temporality, but all demonstrated
nonsignificant risk estimates. Biological plausibility was discussed by two studies. There was no
available evidence to assess the experiment criterion for causality.