Limited association between scalp psoriasis and psoriatic arthritis severity and treatment response

We evaluated whether scalp psoriasis (PsO) is associated with psoriatic arthritis (PsA) severity and/or with treatment response to etanercept.

Patients with moderate-to-severe PsO and active PsA received etanercept 50 mg once weekly for 24 weeks. Patients were stratified according to whether scalp PsO was present at baseline. Demographics and disease characteristics were compared at baseline and after 12 and 24 weeks of treatment with etanercept.

Scalp PsO was present in 273/373 (73.2%) patients; they were significantly younger and a higher proportion were male versus those without scalp PsO. At baseline, the patient global assessment psoriasis score was significantly higher for patients with scalp PsO versus without (67.0 vs. 57.9, p<0.01); tender joint count was significantly higher for patients without scalp PsO (6.0 vs. 5.0, p<0.05). A higher proportion of patients without versus with scalp PsO achieved enthesitis ≤1 at Week 12 (91.5% vs. 81.7%, p<0.05) and dactylitis ≤1 at week 24 (93.9% vs. 85.6%, p<0.05). Patients with scalp PsO showed significantly greater improvements in fatigue and joint pain at weeks 12 and 24, and a greater proportion achieved a score ≤0.5 in the health assessment questionnaire at week 12 (65.2% vs. 53.0%, p<0.05).

Scalp PsO was not clearly associated with PsA severity, and it did not affect treatment response. Patients without scalp PsO exhibited greater improvements in objective joint outcomes, whereas patients with scalp PsO experienced better outcomes in patient-reported outcomes.