Graded activity for workers with low back pain: who benefits most and how does it work?

To identify subgroups of workers absent from work due to low back pain who are more or less likely to return to work earlier as a result of a graded activity intervention, and to investigate whether this intervention is effective in reducing pain-related fears and if so, whether these reductions in pain-related fears mediate return to work.

A subgroup analysis was conducted on data from a previous randomized controlled trial of 134 Dutch airline workers, which found that a behaviorally-oriented graded activity intervention was more effective than usual care in stimulating return to work. The subgroup analyses added interaction terms to a Cox regression model that described the relationship between treatment allocation and return to work over 12 months of followup. Furthermore, we studied the effects of graded activity on pain-related fears and added variables indicating a reduction in pain-related fears to the model in order to investigate their influence on return to work.

Statistically significant interactions were found for disability, fear-avoidance beliefs about physical activity, and fear-avoidance beliefs about work. No indication was found that the reduction in pain-related fears in the graded activity group mediated more favorable return-to-work results in this group.

Workers who perceive their disability to be moderate and workers with moderate scores for fear-avoidance beliefs return to work more rapidly as a result of the graded activity intervention than workers with higher scores. The return to work of workers receiving the graded activity intervention is possibly independent from the reductions in pain-related fears caused by this intervention.