Do work-related mechanical and psychosocial factors contribute to the social gradient in low back pain? A 3-year follow-up study of the general working population in Norway

Objective: The aim of the study was to investigate the extent to which work-related factors contribute to the social gradient in low back pain (LBP). Summary of Background Data. A social gradient in LBP is well established, but only a few studies have examined the extent to which exposure to mechanical and psychosocial work environment factors is a pathway for this gradient. Methods: A randomly drawn cohort from the general population in Norway aged 18 to 66 years was followed up for 3 years (n = 12,550, response rate at baseline = 67%). Eligible respondents were in paid work during 2006 and 2009 (n = 6819). Based on administrative register data respondents were coded into five educational levels (university/college ≥4 years was set as the reference group). Outcome of interest was self-reported moderate or severe LBP at follow-up adjusted for baseline LBP. Results: In total, 11.2% (397 individuals) men and 14.5% (461 individual) women reported LBP at follow-up. There was a strong social gradient ranging from 16.4% (elementary) to 6.4% (university/college ≥4 years). The corresponding figures among women were 22.4% and 7.5%. Corrected for age, LBP at baseline and working hours, educational level was a significant predictor of LBP at follow-up (odds ratios 1.8–2.3 in men...