Sitting versus standing: Does the intradiscal pressure cause disc degeneration or low back pain?

Causal assessment of occupational sitting and low back pain: results of a systematic review

BACKGROUND CONTEXT

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.

PURPOSE

To conduct a systematic review of the scientific literature focused on evaluating the causal relationship between occupational sitting and LBP.

STUDY DESIGN

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.

SAMPLES

Studies reporting an association between occupational sitting and LBP.

OUTCOME MEASURES

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.

Causal assessment of occupational standing or walking and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a widespread musculoskeletal condition that frequently occurs in the working-age population. Numerous occupational physical activities have been implicated in its etiology.

PURPOSE

To conduct a systematic review establishing a causal relationship between occupational standing or walking and LBP.

STUDY DESIGN

Systematic review of the literature.

SAMPLE

Studies reporting an association between occupational standing or walking and LBP.

OUTCOME MEASURES

Numerical association between exposure to standing or walking and the presence 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 for causality, between occupational standing or walking and LBP. A search was conducted 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 expert knowledge. Evaluation of methodological quality was performed using a modified Newcastle-Ottawa Scale.

RESULTS

This search yielded 2,766 citations. Eighteen studies met the inclusion criteria. Five were high-quality studies related to standing, and two were high-quality studies related to walking. For occupational standing and LBP, there was moderate to strong evidence against the association criterion, the only study examining dose response did not support this criterion, four studies examining temporality failed to support this criterion, and only one study discussed the biological plausibility criterion. For occupational walking and LBP, there was moderate evidence against a causal relationship with respect to the association, temporality, dose response, and biological plausibility criteria. No studies assessed the experiment criterion for these activities.

CONCLUSIONS

A summary of existing studies was not able to find any high-quality studies that satisfied more than two of the Bradford-Hill causation criteria for occupational standing or walking and LBP. Based on the evidence reviewed, it is unlikely that occupational standing or walking is independently causative of LBP in the populations of workers studied.