Background/Purpose: In the Care in early RA (CareRA) trial, COBRA Slim, a combination of methotrexate (MTX) with a moderate-dose prednisone step-down-bridge scheme, showed a positive efficacy/tolerability balance in so-called low risk patients (Verschueren et al., 2015). The purpose of this piggy back study is to perform an economic evaluation on the 2 year data of CareRA.

Methods:

Patients with early RA (≤1 year) naïve to DMARDs were stratified based on classic poor prognostic factors (RF/ACPA +, high disease activity, erosions), into high and low risk. Low risk patients were randomized to MTX with a step down bridge glucocorticoid (GC) scheme (COBRA Slim) or MTX without GC (Tight Step Up –TSU-). The treat to target principle was applied, with a low disease activity (DAS28CRP ≤3.2) threshold. Clinical and patient-reported data were collected at each visit (≥10 times in 2 years).

For cost-effectiveness analysis, direct costs of consultations, RA medication (systemic GCs, cs- and bDMARDs, analgesics) and hospitalization costs for serious adverse events over 2 years were considered. As benefits, proportion of patients with DAS28CRP<2.6 at year 2 and area under the curve (AUC) DAS28CRP over 2 years were used. Missing data were imputed per item with expectation maximization.

For cost-utility analysis, utilities were calculated using a validated mapping algorithm (mixed adjusted censored model) for reconstructing EQ-5D scores based on age, sex, HAQ and VAS pain at relevant study visits. Quality-adjusted life years (QALYs) were determined as the time-weighted average of all available EQ-5D scores.

Incremental cost-effectiveness ratios (ICERs) were calculated to compare both treatment strategies. Bootstrapping corrected for bias with 1000 replications was used.

Results:

From the initial CareRA cohort (n=379), cost/benefit data for a 2 year economic analysis of 326 patients was available and of these patients 75 belonged to the Low Risk group: 41 TSU and 34 COBRA Slim. Number of consultations were comparable (±12). Hospitalization costs were >2 times higher in TSU than in COBRA Slim. The mean hospitalization cost for COBRA Slim was €445.32 (CI 213.09-720.53) and €1067.12 (CI 242.34-2273.66) for TSU. There was an outlier in TSU accounting for €26318.43.

Numerically COBRA Slim (79.4% DAS28CRP<2.6) showed a better effectiveness than TSU (75.6%). The cost-effectiveness analysis showed a dominating ICER for COBRA Slim compared to TSU (mean €-167.85/1% remission gained, mean €-2195.16/unit improvement of DAS28CRP AUC over 2 years).

More QALYs were gained with COBRA slim (1.72) compared to TSU (1.59), with significant differences in time (p<0.05). Cost-utility analysis resulted in an ICER of €-3938.54 per QALY.

A sensitivity analysis, leaving out the outlier, resulted in a mean ICER of €0.99/1% remission gained, €12.88/unit improvement of DAS28CRP AUC over 2 years and €23.12 per QALY.

Conclusion: COBRA Slim, a combination of MTX with a step down bridge GC scheme, seems more effective and results in a better quality of life than a tight step up approach. Based on this economic analysis, intensive step down remission induction strategies such as COBRA Slim should also be considered in patients with early RA lacking classical poor prognostic factors.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/step-down-bridge-versus-tight-step-up-therapy-in-patients-with-early-rheumatoid-arthritis-lacking-poor-prognostic-factors-an-economic-point-of-view/