Objective: We evaluated the effectiveness of adalimumab in patients with psoriatic arthritis (PsA) and identified predictors of good clinical responses for joint and skin lesions.
Methods: Patients received adalimumab 40 mg every other week in addition to standard therapy in this prospective, 12-week, open-label, uncontrolled study. We used four definitions of good clinical response: ≥50% improvement in American College of Rheumatology (ACR50) response criteria, good European League Against Rheumatism (EULAR) response, ≥3-grade improvement in Physician's Global Assessment of psoriasis (PGA), and ≥50% improvement in the Nail Psoriasis Severity Index (NAPSI). Response predictors were determined by logistic regression with backward elimination (selection level, 5%).
Results: Of 442 patients, 94% completed 12 weeks of treatment. At Week 12, 74%, 51%, and 32% of the patients achieved ACR20, 50, and 70, respectively; 87% and 61% experienced a moderate and good EULAR response, respectively. The percentage of patients with PGA "Clear/Almost Clear" increased from 34% (baseline) to 68%. The mean NAPSI was reduced by 44%. No new safety signals were detected. A lower Health Assessment Questionnaire Disability Index score, greater pain assessment, male sex, and absence of systemic glucocorticoid therapy were strongly associated with achievement of ACR50 and good EULAR response. In addition, greater C-reactive protein concentration and polyarthritis predicted ACR50, and noninvolvement of large joints predicted good EULAR response.
Conclusion: Adalimumab was effective in patients with PsA. Lower impairment of physical function, greater pain, male sex, and no systemic treatment with glucocorticoids were factors that increased the chance of achieving good clinical response.