Objectives: Risk factors for low-back pain are known to co-occur, but their joint effect has not often been studied. Little is also known about the variation of the risk factors or their effects with age.
Methods: This prospective study assessed the 1-year incidence of low-back pain by age group in a Finnish industrial population. The effects of the baseline variables on the risk of low-back pain in the follow-up were estimated with a log-binomial regression.
Results: Among 2256 blue- and white-collar workers free of low-back pain 12 months preceding the baseline, 21% reported low-back pain after 1-year of follow-up. Physical work load (sum of heavy lifting, awkward postures, and whole-body vibration) predicted low-back pain among those younger than 50 years [highest relative risk (RR) 2.4, 95% confidence interval (95% CI) 1.4-4.2], whereas health behavior (sum of smoking, overweight, and lack of physical exercise) increased the risk only among those 50 years or older (RR up to 2.8, 95% CI 1.4-5.4). Mental stress, dissatisfaction with life, and sleep problems were significant predictors in the group of 40- to 49-year-old workers. Work-related psychosocial factors were not associated with the outcome.
Conclusions: In this study, workers of different ages were affected by slightly different risk factors. The results support the provision of health promotion and stress management as part of programs to prevent work-related low-back pain. In particular, aging workers may benefit from such an integrated approach. More prospective studies on the joint effects of age-specific risk factors of low-back pain are warranted.