Dose-response relationship between work-related cumulative postural exposure and low back pain: a systematic review

OBJECTIVES: To assess the evidence for a dose-response relationship between ROM, duration, and frequency of trunk flexion, and risk of occupational LBP.

METHODS: An electronic systematic search was conducted using Medline, Cumulative Index to Nursing and Allied Health Literature, EMBASE, and Scopus databases focusing on cohort and case-control studies. Studies were included if they focused on non-specific LBP and postural exposure, considering ROM, duration, or frequency of trunk flexion as independent variables. No language restriction was imposed. Included studies were assessed for risk of bias using the Newcastle-Ottawa Scale for observational studies and a summary of evidence is presented.

RESULTS: Eight studies were included and all were methodologically rated as high quality. The included studies yielded a total of 7023 subjects who were considered for risk analysis. Different outcome measures for postural exposure were adopted making meta-analysis difficult to perform.

CONCLUSIONS: We could not find a clear dose-response relationship for work posture exposures and LBP. Limited evidence was found for ROM and duration of sustained flexed posture as risk factor for LBP. We found no evidence for frequency of trunk flexion as a risk factor for LBP.