title: Graded activity for workers with low back pain: who benefits most and how does it work?
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: J Bart
authors.initials: JB
authors.lastname: Staal
authors.forename: Hynek
authors.initials: H
authors.lastname: Hlobil
authors.forename: Albère J A
authors.initials: AJ
authors.lastname: Köke
authors.forename: Jos W R
authors.initials: JW
authors.lastname: Twisk
authors.forename: Tjabe
authors.initials: T
authors.lastname: Smid
authors.forename: Willem
authors.initials: W
authors.lastname: van Mechelen
mesh_terms: D000328:Adult; D001521:Behavior Therapy / Q000379:methods*; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000523:psychology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009786:Occupational Health Services; D016896:Treatment Outcome