Long-term costs and outcomes in psoriatic arthritis patients not responding to conventional therapy treated with tumour necrosis factor inhibitors: the extension of the Psoriatic Arthritis Cost Evaluation (PACE) study

Objective: Poor information on long-term outcomes and costs on tumour necrosis factor (TNF) inhibitors in psoriatic arthritis (PsA) are available. Our aim was to evaluate long-term costs and benefits of TNF- inhibitors in PsA patients with inadequate response to conventional treatment with traditional disease-modifying anti-rheumatic drugs (tDMARDs). Methods: Fifty-five out of 107 enrolled patients included in the study at one year, completed the 5-year follow-up period. These patients were enrolled in 8 of 9 centres included in the study at one year. Patients aged older than 18 years, with different forms of PsA and failure or intolerance to tDMARDs therapy were treated with anti-TNF agents. Information on resource use, health-related quality of life (HRQoL), disease activity, function and laboratory values were collected at baseline and through the 5 years of therapy. Costs (expressed in Euro 2011) and utility (measured by EQ-5D instrument) before TNF inhibitor therapy and after 1 and 5 years were compared. Results: The majority of patients (46 out of 55; 83.6%) had a predominant or exclusive peripheral arthritis and 16.4% had predominant or exclusive axial involvement. There was a statistically significant improvement of the most important clinical variables after 1 year of follow-up. These improvements were maintained also after 5 years. The direct costs increased by approximately €800 per patient-month after 1 year, the indirect costs decreased by €100 and the overall costs increased by more than €700 per patient-month due to the cost of TNF inhibitor therapy. Costs at 5 year were similar to the costs at 1 year. The HRQoL parameters showed the same trends of the clinical variables. EQ-5D VAS, EQ-5D utility and SF-36 PCS score showed a significant improvement after 1 year, maintained at 5 years. SF-36 MCS showed an improvement only at 5 years. Conclusion: The results of our study suggest that TNF blockers have long-term efficacy. The higher cost of TNF inhibitor therapy was balanced by a significant improvement of HRQoL, stable at 5 years of follow-up. Our results need to be confirmed in larger samples of patients.