Biological therapy in the treatment of psoriatic arthritis: economic and epidemiological considerations.

Background: Biological therapies have a significant economic and clinical burden but, in general, lose their effectiveness over time. This study evaluated the medication persistence and costs associated to use of anti-TNF agents for psoriatic arthritis (PsA) treatment. Methods: A historical cohort composed of individuals in Brazil with PsA diagnosis was developed during the period between 2010 and 2015. The difference among the anti-TNF agents was verified by the log-rank test. The predictors of medication non-persistence were identified by Cox regression. The costs were compared by variance analysis with Bonferroni correction. Results: 11,008 patients were analyzed. Adalimumab (51%) was the most used anti-TNF agent. Individuals using adalimumab presented higher medication persistence as compared to etanercept and infliximab. The costs with anti-TNF agents corresponded to 90% of the total costs and were similar among anti-TNF agents. The non-persistence predictors were female sex, younger patients, to live in the Northeastern and Northern regions of Brazil, to use infliximab and etanercept, and have more comorbidities. Conclusion: The direct costs with anti-TNF agents were the main component of total costs. Outpatient and inpatient costs increase when medication persistence decreases. A considerable price reduction of anti-TNF agents has been observed over the years.