Trajectory of radiographic change over a decade: The effect of transition from conventional synthetic disease-modifying antirheumatic drugs to anti-tumour necrosis factor in patients with psoriatic arthritis

Objectives. To describe the trajectory of radiographic progression among patients with PsA who transitioned from conventional synthetic DMARDs to anti-TNF-α inhibitors in routine care. Methods. A retrospective sample of patients with PsA (ClASsification criteria for Psoriatic ARthritis) was taken from the Bath longitudinal cohort. All patients had radiographs of the hands and feet taken: 5 years before (T₀), at the time of (T₁) and 5 years after (T₂) commencing anti-TNF treatment. Radiographs were scored blinded using the PsA-modified Sharpvan der Heijde score (mSvdHS) and for osteoproliferation (Psoriatic Arthritis Ratingen Score) by A.Allard, A.Antony and W.T. This sample size was calculated to ensure 90% power to determine the smallest detectable difference of the mSvdHS to a 5% significance level. Cumulative probability plots were used to determine the probability of radiographic progression pre- (T₀-T₁) and post-(T₁-T₂) anti-TNF treatment. Results. Eighty-four radiographs from 28 patients were selected for inclusion. The median [interquartile range (IQR)] disease duration at baseline (T₀) was 8.5 (0-19.5) years. The interval between T₀-T₁ and T₁-T₂ was 4.2 years (3.34-6.65) and 4.9 years (4.25-5.87), respectively. The median mSvdHS at baseline (T₀) was 8.5 (IQR 1.75-27.5). The median (IQR) rate of change in mSvdHS per year reduced after commencing anti-TNF, from 2.1 (0.88-3.92) between T₀-T₁ to 1.0 (IQR 0.05-2.35) between T₁-T₂ (P = 0.012). Conclusion. The trajectory of damage accumulation over a 10-year period in this observational clinical cohort is low overall. The rate of radiographic damage as measured by the mSvdHS slows following commencement of anti-TNF.