Background/Purpose: To determine the value of acute-phase reactant levels at diagnosis of psoriatic arthritis in predicting the risk of failure of conventional treatment with disease-modifying anti-rheumatic drugs (DMARDs) and the consequent need for biologic treatment with a tumor necrosis factor (TNF) inhibitor.

Methods: Clinical, laboratory, and treatment data were collected from the medical files of a real-life inception cohort of 71 consecutive patients diagnosed with psoriatic arthritis (CASPAR criteria) in 2000-2011 at the rheumatology clinic of a tertiary medical center.  A logistic regression model was used to identify laboratory variables associated with TNF inhibitor use during the disease course.

Results: The cohort included 38 female (53.5%) and 33 male patients of mean age 41±10.4 years; 66 (93%) Jewish and 5 (7%) Arabic. Mean disease duration was 11.56±6.58 years. The most common clinical feature was symmetric polyarthritis (40.8%). 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, at the discretion of the attending rheumatologist. C-reactive protein (CRP) level at diagnosis was positively correlated with need for a TNF inhibitor (p=0.009; hazard ratio = 1.8 95% CI 1.27-1.85). Patients with CRP >0.9 mg/dl at diagnosis started biologic treatment significantly earlier in the disease course than patients with a lower level (p=0.003, hazard ratio = 2.62 95% CI 0.393-2.5).

Conclusion: :  In patients with psoriatic arthritis, CRP ≥0.9mg/dl at diagnosis significantly predicts an inadequate response to conventional  DMARDs and the  probability that a TNF inhibitor will be needed to achieve disease control.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/value-of-c-reactive-protein-level-at-diagnosis-of-psoriatic-arthritis-in-predicting-the-future-need-for-treatment-with-tumor-necrosis-factor-a-inhibitors/