FRI0555 DO TNF INHIBITORS DECREASE RISK OF INCIDENT PSORIATIC ARTHRITIS IN PSORIASIS PATIENTS COMPARED TO THOSE TREATED WITH METHOTREXATE ALONE

Background: Psoriatic arthritis (PsA) is a chronic inflammatory arthritis characterized by joint and entheseal inflammation seen in 30% patients with psoriasis (Pso). In 90% of patients, Pso precedes PsA. Inhibitors of tumor necrosis factor (TNFi) are efficacious treatment options for both, though whether they prevent development of incident PsA in Pso patients is unknown. Objectives: To determine if the use of TNFi reduces the risk of developing psoriatic arthritis in Pso patients compared to those treated with methotrexate alone. Methods: Records on all Pso patients seen at dermatology clinic at our University from January 2006 - June 2019 were reviewed. Patients with any musculoskeletal symptoms were referred to rheumatology and were considered to have PsA if they were diagnosed by a rheumatologist. We used Student’s t-test to compare continuous covariates and Pearson’s chi-squared test or Fisher’s exact test to compare categorical covariates. Variables that were found to be significantly associated with PsA diagnosis were included as potential confounders in the multivariate model. We used Cox proportional hazards models to compare the risk of incident PsA diagnosis for those who initiated TNFi compared to those who initiated methotrexate. A propensity score of TNFi therapy compared to methotrexate therapy was calculated using variables associated with treatment choice and adjusted for in the model. Variables that were associated with both treatment choice and PsA risk were not included in the propensity score. We used backwards stepwise variable selection to build the final model. Results: Out of 154 Pso patients who did not have PsA at baseline, and were started exclusively on a TNFi or methotrexate during the study period,, 85 (55.2%) initiated methotrexate and 69 (44.8%) initiated a TNFi. Mean duration of therapy for those on TNFi was 3.95 (standard error: 0.50) years while mean duration of therapy for those on methotrexate was 1.93 years (standard error: 0.28). Mean follow-up time for those on TNFi was 5.18 years (standard error: 0.49) and for those on methotrexate was 2.71 years (standard error: 0.37) Seventy nine (51.3%) of the cohort were women. Thirty five (22.7%) of subjects developed PsA over the course of the study. After adjusting for propensity score, nail pitting, body surface area (BSA) involved in psoriasis, and depression, TNFi did not significantly reduce the risk of PsA as compared to methotrexate (HR: 0.68 [95% CI: 0.32, 1.41]). Conclusion: Use of TNFi was not associated with a statistically significant decreased risk of incident PsA compared to methotrexate in this study, but a larger cohort with longer follow up will have better power to estimate the true association. Disclosure of Interests: Noah Lininger: None declared, Sarah Siegel: None declared, Sonam Kiwalkar: None declared, Kevin Winthrop Grant/research support from: Bristol-Myers Squibb, Consultant of: AbbVie, Bristol-Myers Squibb, Eli Lilly, Galapagos, Gilead, GSK, Pfizer Inc, Roche, UCB, Alex Ortega Loayza Consultant of: Adviser board for Janssen, Atul Deodhar Grant/research support from: AbbVie, Eli Lilly, GSK, Novartis, Pfizer, UCB, Consultant of: AbbVie, Amgen, Boehringer Ingelheim, Bristol Myer Squibb (BMS), Eli Lilly, GSK, Janssen, Novartis, Pfizer, UCB, Speakers bureau: AbbVie, Amgen, Boehringer Ingelheim, Bristol Myer Squibb (BMS), Eli Lilly, GSK, Janssen, Novartis, Pfizer, UCB