STUDY DESIGN: Prospective cohort study.

OBJECTIVE: To investigate the independent effect of physical workload and childhood socioeconomic status (CSES) on low back pain (LBP) and LBP-related sickness absence among female health care workers.

SUMMARY OF BACKGROUND DATA: The role of physical workload on LBP independently from CSES is still subject to controversy.

METHODS: We used questionnaire data from 1661 female social and health care workers responding to a questionnaire in 2004, 2005, and 2006. We collected information on CSES (parental occupation), physical workload, and LBP-prevalence (no LBP, subchronic LBP, and frequent LBP), and LBP-related sickness absence. The participants were categorized into 5 groups according to CSES (I = highest, V = lowest). Data were analyzed using logistic regression analysis.

RESULTS: Irrespective of CSES, high physical workload increased the odds ratio (OR) of future subchronic LBP (OR = 2.03; 95% confidence interval [CI], 1.61-2.57) and frequent LBP (OR = 2.20; 95% CI, 1.65-3.00), but not LBP-related sickness absence. The odds of subchronic LBP were lower in CSES groups II (OR = 0.62; 95% CI, 0.42-0.93) and III (OR = 0.58; 95% CI, 0.39-0.86) referencing CSES group I, irrespective of physical workload. The odds of short-term LBP-related sickness absence were higher in CSES groups III (OR = 2.78; 95% CI, 1.41-5.47) and IV (OR = 2.18; 95% CI, 1.11-4.27) referencing CSES group I, irrespective of physical workload. We found no interaction between physical workload and CSES.

CONCLUSION: Physical workload and CSES are independently associated with future LBP within a group with similar occupational status.

LEVEL OF EVIDENCE: N/A.