Cost-Effectiveness of TNF-Blocker Injection Spacing for Patients with Established Rheumatoid Arthritis in Remission: An Economic Evaluation from the Spacing of TNF-Blocker Injections in Rheumatoid Arthritis Trial

Abstract

Background: In patients with rheumatoid arthritis in remission, a disease activity-driven tapering of adalimumab or etanercept relying on progressive injection spacing has not been shown to be equivalent to a maintenance strategy at full dose in terms of disease activity in the Spacing of TNF-blocker injections in Rheumatoid ArthritiS Study (STRASS) trial.

Objectives: To evaluate the cost-effectiveness of such a spacing strategy based on the data of the STRASS trial.

Methods: This is a cost-utility analysis of the STRASS trial, a French multicenter 18-month equivalence randomized open-label controlled trial that included patients at stable dose for at least 1 year, in remission for at least 6 months. Effectiveness was assessed in quality-adjusted life-years (QALYs). Costs involved in the study period were assessed from a payer perspective. The decremental cost-effectiveness ratio (DCER) was calculated in the complete cases sample (n = 98). Several sensitivity analyses were conducted and the impact of missing data on DCER estimate was investigated. An acceptability analysis was performed.

Results: In the spacing arm, TNF-blockers were stopped for 34.1% of the patients, tapered for 43.2%, and maintained at full dose for 18.2%. The spacing strategy was associated with less QALYs gain (mean difference of -0.158; 95% confidence interval [CI] -0.085 to -0.232) and reduced costs (mean difference of -€8,440; 95% CI -6,507 to -10,212). The estimated DCER of the spacing strategy over the maintenance at full dose was €53,417 saved per QALY lost (95% CI 32,230 to 104,700).

Conclusions: The spacing strategy appears cost-effective, but the acceptability of such a QALY loss reported to the cost avoided remains to be evaluated, because no consensual threshold has been determined for willingness to accept as compared with willingness to pay.

Keywords: cost-utility; health economics; rheumatoid arthritis; step-down strategy; treatment tapering.