Objectives To investigate the influence of disease duration on treatment response and on the correlation between improvement of patients’ symptoms and improvement in objective measures of inflammation in patients with axial spondyloarthritis (SPA) treated with etanercept (ETA) or adalimumab (ADA).
Methods Data of 112 patients with axial SpA originally enrolled in two (randomized controlled) clincial trials were pooled and analyzed. The following outcome parameters assessed after one year of treatment with ETA (n=66, axial SpA patients with symptom duration <5 (1)) or ADA (n=46; patients with non-radiographic axial SpA, mean symptom duration 6.8 years (2)) were investigated: Bath ankylosing spondylitis (AS) disease activity index (BASDAI), Bath AS functional index (BASFI), AS disease activity score (ASDAS), CRP, and active inflammation in the sacroiliac joints (SIJ) and spine on magnetic resonance imaging (MRI). Comparisons were made between patients with a short (<4 years) versus those with a longer (≥4 years) duration of symptoms. A mixed model approach was applied to compare the improvements between baseline and end of year one between the symptom duration groups after adjustment for baseline and gender. Partial Spearman rank correlations were calculated.
Results Clinical parameters such as BASDAI, BASFI and ASDAS showed significantly better improvement for short vs longer diseased patients (Tab.1). However, regarding changes in the scores for MRI inflammation of SIJ joints and spine and for CRP such a difference between the two groups was not found (Table 1). Furthermore, in short diseased patients the change in BASDAI correlated significantly with the change in SIJ score (rho=0.33, p=0.03) and the change in CRP (rho=0.40, p=0.003). In contrast, in patients with a long disease duration this correlations was poor (change in BASDAI vs change in SIJ score rho=-0.01, p=0.95, change in BASDAI vs change in CRP rho=0.22, p=0.13).
Conclusions 1. Axial SpA patients with short symptom duration respond clearly better to TNF-blocker therapy compared to patients with long symptom duration. 2. While there is a good correlation in short diseased patients between improvement of patients’ reported outcome parameters and objective parameters of inflammation, such a correlation is not found in patients with long symptom duration. These data indicate that patients with longer symptom duration, even in absence of significant structural damage and despite good suppression of inflammation, respond less well to TNF-blockade for reasons which have still to be defined.
Acknowledement: The study was supported by unrestricted grants from Pfizer Pharmaceuticals and Abbott Pharmaceuticals.
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Disclosure of Interest A. Weiß: None Declared, I.-H. Song Speakers Bureau: Abbott, Merck, Pfizer, H. Haibel: None Declared, J. Listing Grant/Research support from: Abbott, Merck, Pfizer, UCB, Roche,BMS, J. Sieper Grant/Research support from: Abbott, Merck, Pfizer, Consultant for: Abbott, Merck, Pfizer, Speakers Bureau: Abbott, Merck, Pfizer