OBJECTIVES: The introduction of biologic therapies has dramatically changed the management of psoriatic arthritis (PsA). The study aimed to estimate long-term costs of biologics in the treatment of psoriatic arthritic patients in the United States. METHODS: We developed a 10-year Markov model describing the treatment pathway of patients with psoriatic arthritis who had failed prior oral DMARD therapy, using monthly cycles. Clinical efficacy data were obtained from published pivotal study results and literature. Costs, resource utilisation and treatment pathways were obtained from literature and expert opinion. Patients transitioned through two lines of biologics (etanercept, infliximab, golimumab or adalimumab as first or second line) followed by best supportive care. Response to therapy was defined as the probability of PsARC response at the end of the trial period. Patients transitioned to the next line of therapy in case of non-response or discontinuation due to other causes (a short-term annual drop-out rate of 32% and a long-term rate of 16.5% were assumed). All-cause death was included and adjusted to reflect the increased mortality associated with PsA. Treatment and administration, monitoring, and hospitalisation costs were included. An annual discount rate of 3% was used. Probabilistic sensitivity analysis was conducted on key model parameters. For each first-line biologic option, average results across second-line biologic therapies were reported. RESULTS: From a third-party payer’s perspective, the estimated 10-year cumulative direct costs per patient were $214,642 (95% Crl: $214,171; $221,074) with etanercept as first-line biologic therapy, $203,140 (95% CrI: $202,632; $208,398) with infliximab, $218,703 (95% Crl: $217,992; $224,255) with golimumab and $208,840 (95% CrI: $208,192; $215,014) with adalimumab. Across scenarios, drug costs represented between 89.4% and 91.1% of total costs, monitoring costs between 4.5% and 6.3%, and hospitalisation costs between 4.3% and 4.9%. CONCLUSIONS: Biologic therapies represent a significant cost burden to payers.