Cost-utility of COBRA-light versus COBRA therapy in patients with early rheumatoid arthritis: the COBRA-light trial

Objective: To evaluate if COmbinatie therapie Bij Reumatoïde Artritis (COBRA)-light therapy is cost-effective in treating patients with early rheumatoid arthritis (RA) compared with COBRA therapy.

Methods: This economic evaluation was performed next to the open-label, randomised non-inferiority COBRA-light trial in 164 patients with early RA. Non-responders to COBRA or COBRA-light received etanercept (50 mg/week) for 3-6 months. The societal perspective analysis took medical direct, non-medical direct and indirect costs into account. Costs were measured with patient cost diaries for the follow-up period of 52 weeks. Bootstrapping techniques estimated uncertainty around the cost-effectiveness ratios, presented in cost-effectiveness planes.

Results: 164 patients were randomised to either COBRA or COBRA-light strategy. At week 52, COBRA-light proved to be non-inferior to COBRA therapy on all clinical outcome measures. The results of the base-case cost-utility analysis (intention-to-treat analyses) revealed that COBRA-light strategy is more expensive (k€9.3 (SD 0.9) compared with COBRA (k€7.2 (SD 0.8)), but the difference in costs were not significant (k€2.0; 95% CI -0.3 to 4.4). Also, both strategies produced similar quality-adjusted life-years (QALYs). The sensitivity analyses showed robustness of these results. In a per-protocol sensitivity analysis, in which costs of etanercept were assumed to be provided as prescribed according to protocol, both arms had much higher costs: COBRA-light: k€11.5 (8.3) compared with k€8.5 (6.8) for COBRA, and the difference in costs was significant (k€2.9; 0.6 to 5.3).

Conclusions: In the base-case cost-utility analysis, the two strategies produced similar QALYs for similar costs. But it is anticipated that if protocol had been followed correctly, the COBRA-light strategy would have been more costly due to additional etanercept costs, for a limited health gain. Given the limited added benefit and high costs of starting etanercept in the presence of low disease activity in our trial, such a strategy needs better justification than is available now.

Trial registration number: 55552928, Results.