title: Comparison of the Bath Ankylosing Spondylitis Disease Activity Index and a modified version of the index in assessing disease activity in patients with ankylosing spondylitis without peripheral manifestations.
abstract: OBJECTIVE
  To compare the original Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) with a modified BASDAI without questions about peripheral arthritis (question 3) and enthesitis (question 4), here termed the mini-BASDAI, as an instrument to assess disease activity in patients with ankylosing spondylitis (AS) without peripheral manifestations.
  
  
  METHODS
  The mini-BASDAI was calculated by omitting questions 3 and 4. The correlation of the original BASDAI and the mini-BASDAI with patient global and other disease parameters was assessed in a total of 692 patients from three AS cohorts including one observational AS cohort and two clinical trial populations treated with non-steroidal anti-inflammatory drugs and tumour necrosis factor alpha inhibitors. Sensitivity to change was assessed by calculating effect sizes.
  
  
  RESULTS
  Up to 70% of AS patients did not have peripheral involvement. Patients with peripheral involvement had higher disease activity in all activity parameters. The mini-BASDAI had higher values compared with the original BASDAI, also in the subgroup with peripheral manifestations. However, the mini-BASDAI did not correlate better with other markers of disease activity compared with the original BASDAI. Furthermore, effect sizes of the original BASDAI and mini-BASDAI were comparable in the treatment trials. Interestingly, approximately 5% of active AS patients with pure axial disease manifestation were identified whose disease activity was underestimated by the original BASDAI.
  
  
  CONCLUSIONS
  On a group level using the mini-BASDAI did not result in an advantage to assess disease activity or in the subgroup without peripheral involvement. In only approximately 5% of AS patients was the mini-BASDAI superior to the original BASDAI.
authors.affiliation: Rheumatology, Charité Medical University, Campus Benjamin Franklin, Berlin, Germany.
authors.forename: I H
authors.initials: IH
authors.lastname: Song
authors.forename: M
authors.initials: M
authors.lastname: Rudwaleit
authors.forename: J
authors.initials: J
authors.lastname: Listing
authors.forename: J
authors.initials: J
authors.lastname: Sieper
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D016032:Randomized Controlled Trials as Topic; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors; D055815:Young Adult
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha