An economic evaluation of stopping versus continuing TNF-inhibitor treatment in rheumatoid arthritis patients in remission or low disease activity: results from the POET randomized trial

OBJECTIVE: To evaluate, from a societal perspective, the incremental cost-effectiveness of withdrawing tumor necrosis factor inhibitors (TNFis) compared to continuation of these drugs within a one-year randomized trial among patients with rheumatoid arthritis (RA) having longstanding stable disease activity or remission. METHODS: Data were collected from a pragmatic, open label trial. Cost-utility analysis was performed using the non-parametric bootstrapping method and a cost-effectiveness acceptability curve was constructed using the net-monetary benefit (NMB) framework, where a willingness-to-accept threshold (WTA) was defined as the minimal cost saved that a patient accepted for each quality-adjusted life year (QALY) lost. RESULTS: 531 patients were randomized to the Stop Group and 186 patients to the Continue Group. Withdrawal of TNFis resulted in more than 60% reduction of the total drug cost, but led to an increase of about 30% in the other healthcare expenditure. Compared to continuation, stopping TNFis resulted in a mean yearly cost saving of €7,133 (95% CI, [€6,071, €8,234]) and was associated with a mean loss of QALYs of 0.02 (95% CI, [0.002, 0.040]). Mean saved cost [95% CI] per QALY lost and per extra flare incurred in the Stop group compared to the Continuation group was €368,269 [€155,132, €1,675,909] and €17,670 [€13,650, €22,721], respectively. At a WTA of €98,438 per QALY lost, the probability that stopping TNFis is cost-effective was 100%. CONCLUSION: Although an official WTA is not defined, the mean saved cost of €368,269 per QALY lost seems acceptable in The Netherlands, given existing data on the willingness-to-pay