Reanalysis of the occurrence of back pain among construction workers: modelling for the interdependent effects of heavy physical work, earlier back accidents, and aging.

OBJECTIVES To re-examine the relation between heavy physical work and the occurrence of sciatic pain among construction workers reported previously to be absent in an epidemiological study. METHODS-Poisson log linear regression was used to model for the frequency of sciatic pain among concrete reinforcement workers and maintenance house painters with adjustment for the interactive effects of earlier back accidents and aging that modified the relation. RESULTS Concrete reinforcement work not only had a direct effect on the frequency of sciatic pain, but it also contributed significantly to the risk indirectly through earlier back accidents. The risk of sciatic pain increased from age 25 to 54 in a different manner for a worker depending on his occupational group and record of back accidents. CONCLUSIONS Epidemiological studies on low back pain need to be analysed with sound methodology. This is important in view of future meta-analyses that will be performed for the purpose of providing guidelines on the prevention of back disorders in heavy physical work.