Active disease requiring TNF-alpha-antagonist therapy can be well discriminated with different ASDAS sets: a prospective, follow-up of disease activity assessment in ankylosing spondylitis.

OBJECTIVES: To evaluate the validity of different ASDAS sets to assess disease activity in ankylosing spondylitis (AS) in comparison to standard activity assessment tools in routine clinical setting and to determine the best cut-off values for deciding active disease requiring TNF-α antagonist therapy.
METHODS: Two hundred consecutive AS patients (M/F:104/96) were enrolled. Mean (SD) age was 40.3 (11.7) and disease duration was 11 (8.5) years. Disease activity was assessed by four different ASDAS sets, BASDAI, patient and physicians' global assessments, ESR and CRP. The correlation between different parameters and ASDAS scores of patients requiring TNF-α antagonist therapy were determined.
RESULTS: At the time of the assessment 18.5% of the patients were only having NSAIDs, 43% were receiving sulphasalazine and/or methotrexate and 38.5% were under TNF-α antagonists. After the evaluation, 36 (18%) patients were decided to require TNF-α antagonist therapy, 33 (16.5%) patients were started sulphasalazine or methotrexate or their dose increased and 131 (65.5%) patients were decided to be stable without any requirement for a change in therapy. The patients requiring new-TNFα antagonist therapy had significantly higher ASDAS values. The ROC curve analysis revealed best-cut off values for ASDAS sets (ASDAS A: 3.28, ASDAS B: 3.07, ASDAS C: 2.38 and ASDAS D: 3.1) When standardised mean differences were compared, ASDAS B was the best set within the others, but not significantly different from other ASDAS sets and standard assessment tools except acute-phase reactants.
CONCLUSIONS: ASDAS sets perform well to discriminate TNF-α antagonist requirement in advanced AS patients. However BASDAI and patient's or physician's global assessments also had acceptable performances in our clinical setting.