title: What do we miss? ASAS non-responders on anti-TNF therapy show improvement in performance-based physical function.
abstract: OBJECTIVE
  A prospective study was conducted in order to establish whether AS patients, who are defined as non-responders after 3 months of anti-TNF therapy, show improvement on performance-based tests of physical functioning.
  
  
  METHODS
  At baseline and 3 months after the start of anti-TNF therapy, AS patients completed seven performance-based tests of physical functioning, questionnaires on self-reported physical functioning (BASFI) and disease activity (BASDAI), and a pain and a global patient assessment. The concordance between ≥ 20% intra-individual improvement on the performance-based test of physical functioning and (i) response to anti-TNF therapy [Assessment of SpondyloArthritis International Society 20% (ASAS20) response] and (ii) ≥ 20% intra-individual improvement on self-reported physical functioning (BASFI) was assessed.
  
  
  RESULTS
  One hundred AS patients were included, of which 82 patients completed all tests at both time points. After 3 months of anti-TNF therapy, 27 (32.9%) patients were categorized as non-responders according to the ASAS20 response criteria. Improvement in performance-based physical functioning was seen in 13 of the 27 non-responders (48.1%) (i.e. n = 13/82 = 15.9% of the total group). Furthermore, 30 (36.6%) patients showed no improvement on self-reported physical functioning (BASFI). However, 17 of the 30 (56.7%) patients did improve on the performance-based tests of physical functioning (i.e. n = 17/82 = 20.7% of the total group).
  
  
  CONCLUSIONS
  After 3 months of anti-TNF therapy, performance-based tests of physical functioning showed improvement in 48.1% of the ASAS20 non-responders. With these performance-based tests, new information on outcome after anti-TNF therapy can be generated. Using performance-based tests alongside the BASFI could have additional value in the evaluation of outcomes for patients receiving anti-TNF therapy.
authors.affiliation: Reade, Centre for Rehabilitation and Rheumatology, Dr Jan van Breemenstraat 2, PO Box 58271, 1040 HG Amsterdam, The Netherlands. s.v.weely@reade.nl.
authors.forename: Salima F E
authors.initials: SF
authors.lastname: van Weely
authors.forename: J Christiaan
authors.initials: JC
authors.lastname: van Denderen
authors.forename: Martijn P M
authors.initials: MP
authors.lastname: Steultjens
authors.forename: Michael T
authors.initials: MT
authors.lastname: Nurmohamed
authors.forename: Ben A C
authors.initials: BA
authors.lastname: Dijkmans
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
authors.forename: Irene E
authors.initials: IE
authors.lastname: van der Horst-Bruinsma
mesh_terms: D000328:Adult; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020127:Recovery of Function; D057566:Self Report; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000188:drug therapy* / Q000503:physiopathology; D017211:Treatment Failure; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha
keywords: ankylosing spondylitis; outcome assessment; performance-based tests; physical functioning