The effectiveness of a biologic agent on axial manifestations of psoriatic arthritis. A twelve months observational study in a group of patients treated with etanercept.

OBJECTIVES To investigate the effectiveness of etanercept on axial manifestations of a group of patients with established psoriatic arthritis (PsA). METHODS This was a multicentre observational study. PsA was classified based on the CASPAR criteria. Inclusion criteria were refractory PsA with axial manifestations and suitability for anti TNF-α therapy. Effectiveness was defined according to the ASAS response criteria (BASDAI: 50% relative or absolute change of 20mm and expert opinion in favour of continuation), and on the improvements of BASFI, anthropometric measures, PASI, ESR and CRP at 12 months. PASI 50 and 75 were also assessed, as well as the ACR20 and ACR50 response criteria for patients with peripheral arthritis. Comparisons between baseline and after 12-month treatment were done using the Wilcoxon signed rank test for the end-points considered. RESULTS The study included 32 patients (25/7 M/F; median age 51yrs; 25th-75th percentiles: 34.5-58.7; median disease duration 14.5 yrs; 25th-75th percentiles: 9.2-17.00). Effectiveness of etanercept was observed in 72% of patients for the BASDAI (p<0.001), in 68% for the BASFI (p<0.001), in 76% for ESR (p<0.001) and in 68% of patients for CRP (p<0.01). The PASI improved in 72% of patients treated (p<0.0001), while PASI 50 and PASI 75 was reached in 81% and 55% of patients, respectively. ACR 20 and 50 was reached in 78 and 56% of patients with peripheral involvement respectively. CONCLUSIONS The present study has shown that etanercept is effective on axial manifestations of established PsA, confirming the positive effects of anti TNF-α therapy on clinical manifestations of the disease.