title: Work-related outcomes in randomised placebo-controlled pain trials: a systematic review and meta-analysis.
abstract: BACKGROUND
  Chronic painful conditions have an important influence on the ability to work. Work-related outcomes, however, are not commonly reported in publications on trials investigating the treatment of chronic painful conditions. We aim to provide an overview of the reporting of work-related outcomes in such trials and investigate the relationship between work-related outcomes and pain outcomes.
  
  
  METHODS
  We conducted a systematic literature search in PubMed with the aim of identifying randomised placebo-controlled clinical trials investigating treatments for chronic painful conditions or rheumatic diseases that also reported on work-related outcomes. Methodological study quality was assessed with the Oxford Quality Scale (OQS). Meta-analyses were conducted for the outcomes of interference with work and number of patients with at least 30% reduction in pain intensity (30% pain responders). The correlation between work-related and pain outcomes was investigated with regression analyses.
  
  
  RESULTS
  We included 31 publications reporting on 27 datasets from randomised placebo-controlled trials (with a total of 11,434 study participants) conducted in chronic painful or rheumatic diseases and reporting on work-related outcomes. These 31 publications make up only about 0.2% of all publications on randomised placebo-controlled trials in such conditions. The methodological quality of the included studies was high; only nine studies scored less than four (out of a maximum five) points on the OQS. Sixteen different work-related outcomes were reported on in the studies. Of 25 studies testing for the statistical significance of changes in work-related outcomes over the course of the trials, 14 (56%) reported a significant improvement; the others reported non-significant changes. Eight studies reported data on both interference with work and 30% pain responders: meta-analyses demonstrated similar, statistically significant improvements in both these outcomes with active therapy compared to placebo and regression analysis showed that these outcomes were correlated.
  
  
  CONCLUSIONS
  Despite the importance of pain as a reason for decreased ability to work, work-related outcomes are reported in substantially less than 1% of publications on placebo-controlled trials in chronic painful and rheumatic diseases. Work-related outcomes and pain responder outcomes are closely related.
authors: Department of Medical Statistics, University Medical Center Göttingen, Humboldtallee 32, 37073 Göttingen, Germany ; Institute of Occupational, Social and Environmental Medicine, University Medical Center Göttingen, Waldweg 37 B, 37073 Göttingen, Germany.
authors: Ingmar
authors: I
authors: Wolf
authors: Department of Medical Statistics, University Medical Center Göttingen, Humboldtallee 32, 37073 Göttingen, Germany.
authors: Tim
authors: T
authors: Friede
authors: Institute of Occupational, Social and Environmental Medicine, University Medical Center Göttingen, Waldweg 37 B, 37073 Göttingen, Germany.
authors: Ernst
authors: E
authors: Hallier
authors: Institute of Occupational, Social and Environmental Medicine, University Medical Center Göttingen, Waldweg 37 B, 37073 Göttingen, Germany.
authors: Sebastian
authors: S
authors: Straube
keywords: Chronic painful conditions; Randomised controlled trials; Rheumatic diseases; Work-related outcomes