Elevated C-reactive protein level predicts earlier treatment with tumor necrosis factor-alpha inhibitors in psoriatic arthritis

Background: Tumor necrosis factor-alpha (TNFα) inhibitors are indicated for patients with psoriatic arthritis (PsA) in whom conventional disease-modifying anti-rheumatic drugs (DMARDs) are insufficient to achieve disease remission. Objectives: To determine the value of acute-phase reactant levels at diagnosis of psoriatic arthritis in predicting the need for biologic treatment with TNFα inhibitors. Methods: We conducted a longitudinal observational study of an inception cohort of 71 consecutive patients diagnosed with psoriatic arthritis. C-reactive protein (CRP) was assayed for all patients at their first visit. Results: All patients were treated with one or more DMARDs, mainly methotrexate (81.6%). Thirty-seven patients (52.11%) had an inadequate response and received at least one TNF inhibitor. CRP level at diagnosis was positively correlated with need for a TNF inhibitor (P = 0.009, HR 1.8, 95%CI 1.27-1.85). Patients with CRP > 0.9 mg/dl at diagnosis started biologic treatment significantly earlier than patients with a lower level (P = 0.003, HR 2.62, 95%CI 0.393-2.5). Conclusions: In patients with psoriatic arthritis, CRP ≥ 0.9 mg/dl at diagnosis significantly predicts an earlier need for a TNF inhibitor to achieve disease control.