Prevalence and predictors of tumour necrosis factor inhibitor persistence in psoriatic arthritis

Objectives. To evaluate TNF-a inhibitor (TNFi) persistence when used as first-or second-line biologic therapy for the management of PsA, and to determine baseline clinical and laboratory parameters associated with TNFi persistence. Methods. A retrospective single-centre cohort study was performed on all patients with PsA initiated on TNFi therapy between 2003 and 2015. Demographic, clinical and laboratory characteristics were compared with TNFi persistence, using Kaplan-Meier survival and Cox proportional hazards models. Results. One hundred and eighty-eight patients with PsA were prescribed TNFi therapy as first-line biologic therapy over a period of 635 person-years [46% male, mean (S.D.) age 47.3 (11.4) years; median (interquartile range) disease duration 11 (7-16) years]. At 12 months of follow-up 79% of patients persisted with TNFi therapy, and 73% at 24 months. Of those discontinuing TNFi, 35% stopped due to primary inefficacy, 22% secondary inefficacy and 43% adverse events. Multivariable analysis identified female sex (hazard ratio (HR) 2.57; 95% CI: 1.26, 5.24; P = 0.01) and the presence of metabolic syndrome-related comorbidities (HR = 2.65, 95% CI: 1.24, 5.69; P = 0.01) as predictors of lower persistence. Of 32 cases treated with a second TNFi, persistence at 12 months was 56%. TNFi persistence was 2-fold less likely in these 32 cases compared with first-line TNFi users (HR = 2.02, 95% CI: 1.20, 3.42; P = 0.01). Conclusion. Patients with PsA who are female and have metabolic syndrome-related co-morbidities have lower TNFi persistence. Although persistence was lower in patients who had switched to a second TNFi, a substantial proportion of these cases responded, advocating switching to a second TNFi as a valid therapeutic strategy.