Background Data on longer term efficacy and tolerance of biologic therapies in psoriatic arthritis (PsA) are emerging. Persistence with the first TNF inhibitor (TNFi) at one year is estimated at 70-87%. Data on the benefit of switching between TNFi are limited but persistence with a second agent at one year is reported as 74-81%.

Objectives To investigate the treatment response, drug survival and outcome with the first and subsequent biologic agents in patients with PsA.

Methods Data were collected from a prospective single-centre cohort of PsA patients who were started on a biologic agent between 1st Jan 2003 – 1st Sept 2010.

Results Seventy-one patients started a biologic agent of whom 96% had polyarticular disease. The median follow-up was 36 months, median age at start of biologic 47y and median disease duration 10y. The most frequently prescribed first biologic agent was etanercept (58%) followed by adalimumab (35%) and infliximab (7%).

Thirty-six percent started a biologic agent as monotherapy, 49% started in combination with one DMARD and 13% with two DMARDs. Ninety-six percent fulfilled the Psoriatic Arthritis Response Criteria (PsARC) where completed.

Persistence with the first biologic was 92% at 6 months, 87% at 12 months, 74% at 24 months and 70% at 36 months. Six patients (8.4%) stopped due to secondary inefficacy (after 12 weeks) and 16 (23%) stopped due to an adverse event.

Nineteen patients switched to a second biologic agent (6 due to secondary inefficiency and 13 due to an adverse event). Persistence was 67% at 6 months and 53% at 12 months. One patient stopped due to primary inefficacy, 2 due to secondary inefficacy and 7 had an adverse event. Of the 6 patients who had switched to a second agent because of secondary inefficacy, one continued on the second agent, one switched again because of primary inefficacy, 2 switched again because of secondary inefficacy and 2 switched again because of an adverse event. Of the 13 patients who switched to a second agent because of an adverse event, 8 continued on the second agent, one stopped biologic therapy and 3 switched again because of an adverse event. One patient was pending switch to a 3rd biologic at the time of analysis.

Eight patients switched to a third biologic. Six continued on the third agent (median follow up after switching 26 months). Two switched to a 4th agent (ustekinumab) because of secondary inefficacy and remained on the 4th agent at 4 and 11 months follow up respectively.

Median percentage improvements with the first biologic at 12 and 24 months respectively were 79% and 100% in swollen joint count, 77% and 83% in tender joint count, 50% and 56% in Health Assessment Questionnaire, 67% and 61% in Psoriasis Area and Severity Index, 89% and 100% in Dermatology Life Quality Index and 100% and 100% in the Bath Nail Score.

Conclusions Persistence with the first biologic agent in this cohort was 87% at 12 months, 74% at 24 months and 70% at 36 months. The response to the first biologic agent was sustained at 24 months across joint, skin, nail and quality of life measures. Persistence with the second biologic agent was 53% at 12 months. Patients who switched to a second biologic agent because of adverse event were more likely to continue with the second agent than those who switched because of secondary inefficacy.

Disclosure of Interest D. Wallis Grant/Research support from: The work was partly supported by an unrestricted research grant from Abbott Laboratories, D. Jadon: None Declared, W. Tillett: None Declared, N. Waldron: None Declared, C. Cavill: None Declared, N. McHugh: None Declared, E. Korendowych: None Declared