Background Although dose tapering of tumour necrosis factor (TNF)-blockers in ankylosing spondylitis (AS) showed a comparable clinical efficacy with favourable safety and cost in some studies, there has been no investigation comparing the radiographic progression of patients with tapering regimen versus patients with standard-dose treatment.
Objectives To investigate the impact of dose reduction of TNF-blockers on radiographic progression in the AS over 4 years
Methods One hundred sixty five patients treated with etanercept or adalimumab were selected from single-centre, prospective observational cohort based on the availability of cervical and lumbar radiographs at baseline and after 2 and/or 4 years of the treatment. Radiographs were scored using modified Stokes AS spinal score (mSASSS) by two independent readers. Radiographic progression of patients treated with standard-dose (standard-dose group, n=49) was compared with that of patients who tapered the dosage during the TNF-blocker treatment (tapering group, n=116) using linear mixed models.
Results Demographic and clinical factors at baseline between two groups were not significantly different except for higher initial BASDAI (7.1 vs. 6.3, p=0.003) in the standard-dose group. Baseline mSASSS (SD) of the standard-dose group and the tapering group were 17.3 (17.7) and 11.0 (16.0), respectively (p=0.059). At 2 years after the treatment, mean dose quotient (SD) of the tapering group was 0.59 (0.17) and time to first dose reduction (SD) was 36.6 (28.4) weeks. During the observation period, the rate of radiographic progression in the overall patients was 0.90 mSASSS unit/year. Rate of progression was significantly higher in patients with longer disease duration (≥10 years), elderly patients (≥40 years old), smokers, or patients with a hip involvement at baseline.
Radiographic progression over 4 years between two treatment strategies was similar after the adjustment for baseline status. However, in the subgroup of patients who have syndesmophytes at baseline, it occurred significantly faster in the tapering group (1.30 mSASSS unit/year vs. 1.82 mSASSS unit/year, p=0.008) (figure). This result was concordant when radiographic progression was assessed by the development of new syndesmophytes (0.52/year vs. 0.73/year, p=0.047).
Conclusions Dose tapering strategy of TNF-blockers is associated with more rapid radiographic progression in AS patients who have syndesmophytes at baseline.
Závada J, et al. A tailored approach to reduce dose of anti-TNF drugs may be equally effective, but substantially less costly than standard dosing in patients with ankylosing spondylitis over 1 year: a propensity score-matched cohort study. Ann Rheum Dis 2016;75:96–102.
Disclosure of Interest None declared