title: Effect of biological therapy on work participation in patients with ankylosing spondylitis: a systematic review.
abstract: OBJECTIVE
  To review systematically the effect of biological treatment in patients with ankylosing spondylitis (AS) on three work outcomes: work status, absence from paid work and at-work productivity.
  
  
  METHODS
  A systematic literature search was performed (Pubmed, Embase, Cochrane Library) to identify relevant articles. Risk of bias of included studies was assessed using the Cochrane guidelines for cohorts and randomised controlled trials (RCTs). Data were extracted using a self-composed data extraction form. Owing to extensive interstudy heterogeneity, narrative summaries were used to present the data.
  
  
  RESULTS
  Nine studies were included (six uncontrolled cohorts, one population-controlled cohort and two RCTs) that reported on 39 comparisons. Overall, 961 patients were treated with three different tumour necrosis factor α inhibitors (etanercept, infliximab, adalimumab). For presenteeism and absence from work, most comparisons showed improvement in favour of biological agents, but not all comparisons were statistically significant and they usually concerned before-after analyses. For work status, changes were less often positive, but studies dealt with patients with longstanding AS, lacked power and had a relatively short follow-up.
  
  
  CONCLUSIONS
  Although trends towards beneficial effects of biological agents in longstanding AS were seen on all work outcomes, the methodological limitations in the studies included hampers clear conclusions. Since the majority of studies were (extensions of) controlled trials, the generalisability of the effect of biological agents on work participation in real life should be further studied in larger (population-controlled) studies. The effect of biological agents in patients with early disease has not yet been examined.
authors.affiliation: Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Lennart R A
authors.initials: LR
authors.lastname: van der Burg
authors.forename: Marieke M
authors.initials: MM
authors.lastname: Ter Wee
authors.forename: Annelies
authors.initials: A
authors.lastname: Boonen
mesh_terms: D000041:Absenteeism; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001688:Biological Products / Q000627:therapeutic use*; D004651:Employment; D006801:Humans; D012307:Risk Factors; D013167:Spondylitis, Ankylosing / Q000188:drug therapy* / Q000453:epidemiology / Q000534:rehabilitation*
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products