Background/Purpose: socioeconomic costs of rheumatoid arthritis (RA) are very high. Biologic therapies with different biologic targets are now available for moderate to severe RA, and these drugs increased the overall direct costs of RA. Thus, therapeutic strategies to improve the cost-effectiveness of the biologics are welcome. Rituximab (RTX) is generally administered intravenously 1 g x 2 (day 1- day 15, regimen 1) and the retreatment is scheduled at the time of clinical relapse. A more intensive regimen has been proposed: 1 g x 2 (day 1- day 15, regimen 2) every six months, following  the “treat to target” approach (1). The aim of this study is to compare the cost-effectiveness of two regimens of RTX administration in longstanding RA patients.

Methods: an observational retrospective study was conducted in three Centers. One hundred and two patients suffering from moderate to severe longstanding RA (disease duration more than two years) were enrolled. 47 followed regimen 1, while 55 patients were treated with regimen 2. All the patients were followed for at least one year. A cost effectiveness analysis (CEA) based on a Markov Model were conducted on the basis of sample data collected and scientific literature. Markov Model represented natural evolution of RA and was composed by four states: Treatment, Response, Relapse, and Death. An hypothetical cohort of 300.000 populated the model and was followed till death adopting a societal perspective. Pharmaceutical, direct health, and indirect costs were estimated as well as health quality. Univariate and probabilistic sensitivity analysis (PSA) were done. CEA was conducted for the whole sample of patients and for a subgroup of  them (those with rheumatoid factor and/or anti-cyclic citrullinated peptide).

Results: results for the overall sample show at 10-20-30 year that regimen 1 is less costly and associated with an higher QoL compared to regimen 2. PSA at 10 years estimated a probability of 94.20%  for regimen 1 to be cost-effective given a willingness to pay of 30000 € /QALY. The subanalysis in seropositive patients showed that regimen 1 is more cost-effectiveness than regimen 2. PSA at 10 years estimated a probability of 90%  for regimen 1 to be cost-effective given a willingness to pay of 30000 € /QALY. Significant differences in the baseline HAQ and DAS 28 scores were estimated (p<0.0001, and p=0.002, respectively, Mann Whitney U test), although both groups of patients showed a median baseline high disease activity and disability [regimen 1 vs regimen 2: 1.5 (0.5-2.75) vs. 2.7 (0.375-3) for HAQ, and 5.9 (3.5-8.4) vs. 5.0 (2.9-7.0) for DAS28]. At 12 month, the difference in the HAQ scores persisted (p=0.0004), while there was no difference in the DAS28 (p=0.86).

Conclusion: in longstanding RA, a less intensive regimen of RTX with retreatment at clinical relapse seems to be at least equivalent of the more intensive regimen with retreatment every six months. RTX regimen choice may be oriented by the clinical judgment on the balance between the disease activity and the level of disability, and the evaluation of the irreversible/reversible component ratio in the HAQ score. A similar evaluation in patients with early disease is required.

1. Emery P, et al. Rheumatology (Oxford). 2011;50(12):2223-32.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/cost-effectiveness-analysis-of-two-rituximab-based-therapeutic-regimens-for-longstanding-rheumatoid-arthritis/