Risk factors for radiographic progression in psoriatic arthritis: subanalysis of the randomized controlled trial ADEPT.
BACKGROUND
To identify independent predictors of radiographic progression in psoriatic arthritis (PsA) for patients treated with adalimumab or placebo in the Adalimumab Effectiveness in PsA Trial (ADEPT).


METHODS
Univariate analyses and multivariate linear regression analyses assessed risk for radiographic progression (change in modified total Sharp score, DeltamTSS>0.5) from baseline to week 24 for C-reactive protein (CRP) and other baseline variables, and for 24-week time-averaged CRP (univariate analysis only). Subanalyses determined mean DeltamTSS for CRP subgroups. Analyses were post hoc, with observed data.


RESULTS
One hundred and forty-four adalimumab-treated patients and 152 placebo-treated patients were assessed. Mean CRP was 64% lower by week 2 with adalimumab and essentially unchanged with placebo. Univariate analyses indicated that elevated CRP at baseline and time-averaged CRP were strongly associated with radiographic progression for placebo-treated patients but not for adalimumab-treated patients. Multivariate analysis confirmed that elevated baseline CRP was the only strong independent risk factor for radiographic progression (for CRP>or=1.0 mg/dl: odds ratio=3.28, 95% confidence interval=1.66 to 6.51, P<0.001). Adalimumab treatment reduced risk of progression approximately fivefold. The difference between mean DeltamTSS for adalimumab versus placebo was greatest for patients with baseline CRP>or=2.0 mg/dl (-0.5 vs. 2.6).


CONCLUSIONS
Systemic inflammation in PsA, as indicated by elevated baseline CRP, was the only strong independent predictor of radiographic progression. This association was observed predominantly for placebo-treated patients. Adalimumab treatment substantially reduced the overall risk of radiographic progression, and provided greatest radiographic benefit for patients with the greatest CRP concentrations at baseline.


BACKGROUND
Trial registration: NCT00195689.
Gladman
Dafna D
DD
University of Toronto, 399 Bathurst Street, Room 1E-410B, Toronto, Ontario M5T 2S8, Canada.
Mease
Philip J
PJ
Choy
Ernest H S
EH
Ritchlin
Christopher T
CT
Perdok
Renee J
RJ
Sasso
Eric H
EH
D000068879:Adalimumab; D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D015535:Arthritis, Psoriatic / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D018450:Disease Progression; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011859:Radiography; D012307:Risk Factors; D016896:Treatment Outcome
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents; D002097:C-Reactive Protein; D000068879:Adalimumab