Objective: To evaluate the effect of infliximab on progression of structural damage over 1 year in patients with active psoriatic arthritis (PsA) enrolled in the Induction and Maintenance Psoriatic Arthritis Clinical Trial 2.
Methods: In this double-blind, placebo-controlled study, 200 patients with active PsA were randomly assigned (1:1 ratio) to receive infusions of infliximab (5 mg/kg) or placebo at weeks 0, 2, and 6, and every 8 weeks thereafter through week 54. At week 24, patients initially assigned to receive placebo crossed over to receive infliximab (5 mg/kg). Based on predefined criteria, patients randomized to receive placebo could enter early escape by receiving infliximab (5 mg/kg) starting at week 16, and patients randomized to receive infliximab could have the dose increased to 10 mg/kg starting at week 38. Patients were analyzed according to the treatment they were randomized to receive. Radiographs of hands and feet were obtained at baseline and at weeks 24 and 54. Two readers blinded to treatment assignment and radiograph sequence independently evaluated erosions and joint space narrowing using the Sharp/van der Heijde scoring method modified for PsA.
Results: At week 24, patients randomized to receive infliximab 5 mg/kg had significantly less radiographic progression compared with patients randomized to receive placebo, with mean +/- SD changes from baseline in the total Sharp/van der Heijde score of -0.70 +/- 2.53 and 0.82 +/- 2.62, respectively (P < 0.001). At week 54, mean +/- SD changes from baseline in the total Sharp/van der Heijde score were -0.94 +/- 3.40 in patients randomized to receive infliximab and 0.53 +/- 2.60 in those receiving placebo/infliximab (P = 0.001).
Conclusion: Infliximab significantly inhibits radiographic progression in patients with PsA as early as 6 months after starting treatment, and the beneficial effect continues through 1 year of infliximab therapy.
Trial registration: ClinicalTrials.gov NCT00051623.