Responsiveness of the Ankylosing Spondylitis Disease Activity Score (ASDAS) and clinical and MRI measures of disease activity in a 1-year follow-up study of patients with axial spondyloarthritis treated with tumour necrosis factor alpha inhibitors.
OBJECTIVE
To investigate construct validity and responsiveness of the novel ankylosing spondylitis (AS) disease activity score (ASDAS) in patients with spondyloarthritis (SpA).


METHODS
In a 46-week prospective longitudinal multicentre study of 60 patients with SpA (80% men, median age 40 years (range 21-62)) treated with tumour necrosis factor alpha (TNFalpha) inhibitors (infliximab, n=41; etanercept, n=13; adalimumab, n=6), the responsiveness of ASDAS, conventional clinical measures of disease activity and treatment response and the Berlin MRI sacroiliac joint (SIJ) and lumbar spine inflammation scores were compared.


RESULTS
After 22 weeks, 58.3% of the patients were clinical responders (50% or 20 mm reduction in the Bath AS Disease Activity Index (BASDAI)). At baseline, clinical responders had significantly higher median (range) ASDAS than non-responders (4.15 (1.98-6.04) vs 2.99 (2.05-6.19), p=0.008). Changes in ASDAS correlated with changes in clinical measures of disease activity (including BASDAI (rho=0.76) and C-reactive protein (CRP) (0.79)), MRI SIJ inflammation (0.46) and MRI total inflammation scores (0.34). Patients with higher BASDAI or Assessment of SpondyloArthritis International Society (ASAS) responses obtained more profound reductions in ASDAS. ASDAS had the highest responsiveness with an effect size of 2.04 and a standardised response mean of 1.45, whereas BASDAI (effect size 1.86; standardised response mean 1.36) and CRP (effect size 0.63; standardised response mean 0.70) were less responsive. Linear regression showed that a change in BASDAI of 20 mm or 50% corresponded to a change in ASDAS of 1.38 and 1.95, respectively.


CONCLUSIONS
ASDAS demonstrates construct validity and high responsiveness during treatment with TNFalpha inhibitors in patients with SpA. The proposed thresholds for disease activity and treatment response need further validation. Trial registration number NCT00133315.
Pedersen
Susanne Juhl
SJ
Department of Rheumatology, C Post 535, Gentofte University Hospital, Niels Andersens Vej 65, DK-2900 Hellerup, Denmark. susanne_juhl_ped@dadlnet.dk
Sørensen
Inge Juul
IJ
Hermann
Kay-Geert A
KG
Madsen
Ole Rintek
OR
Tvede
Niels
N
Hansen
Michael Sejer
MS
Thamsborg
Gorm
G
Andersen
Lis Smedegaard
LS
Majgaard
Ole
O
Loft
Anne Gitte
AG
Erlendsson
Jon
J
Asmussen
Karsten
K
Johansen
Julia S
JS
Jurik
Anne Grethe
AG
Møller
Jakob
J
Hasselquist
Maria
M
Mikkelsen
Dorrit
D
Skjødt
Thomas
T
Hansen
Annette
A
Ostergaard
Mikkel
M
D000068879:Adalimumab; D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D004812:Epidemiologic Methods; D000068800:Etanercept; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000627:therapeutic use; D000069285:Infliximab; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use; D012446:Sacroiliac Joint / Q000473:pathology; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000188:drug therapy* / Q000473:pathology; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*; D055815:Young Adult
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab; D000068879:Adalimumab; D000068800:Etanercept