As part of its single technology appraisal (STA) process, the National Institute for Health and Care Excellence (NICE) invited the manufacturer (Sanofi Genzyme) of sarilumab (SAR; Kevzara®) to submit evidence of its clinical effectiveness and cost-effectiveness for previously treated moderate or severe rheumatoid arthritis (RA). The School of Health and Related Research Technology Appraisal Group at the University of Sheffield was commissioned to act as the independent Evidence Review Group (ERG). The ERG produced a detailed review of the evidence for the clinical effectiveness and cost-effectiveness of the technology, based upon the company's submission to NICE. The clinical effectiveness evidence in the company's submission for SAR was based predominantly on five randomised controlled trials comparing the efficacy of SAR against adalimumab, tocilizumab or placebo. The clinical effectiveness review identified no head-to-head evidence on the efficacy of SAR against all the comparators within the scope. Therefore, the company performed three network meta-analyses (NMAs) in two different populations: two in patients who had had an inadequate response to conventional disease-modifying antirheumatic drugs (cDMARDs) (one for combination therapies and one for monotherapies) and the other one in patients who had had an inadequate response to tumour necrosis factor inhibitors (TNFis). The company's NMAs concluded that SAR in combination with cDMARDs or as monotherapy has a statistically superior efficacy to cDMARDs and a comparable efficacy to most biologic disease-modifying antirheumatic drugs (bDMARDs) in both populations. The company submitted a Markov model that assessed the cost-effectiveness of SAR from the perspective of the National Health Service (NHS) and Personal Social Services in seven different populations: (1) patients with severe RA who have had an inadequate response to cDMARDs (cDMARD-IR); (2) cDMARD-IR patients with severe RA for whom methotrexate (MTX) is contraindicated or not tolerated; (3) patients with severe RA who have had an inadequate response to a TNFi (TNFi-IR); (4) TNFi-IR patients with severe RA for whom rituximab (RTX) is not an option; (5) TNFi-IR patients with severe RA for whom MTX is contraindicated or not tolerated; (6) TNFi-IR patients after RTX; and (7) cDMARD-IR patients with moderate RA whose 28-joint Disease Activity Score (DAS28) is between 4.0 and 5.1. The company's economic evaluation resulted in incremental cost-effectiveness ratios (ICERs) lower than £20,000 per quality-adjusted life year (QALY) gained for SAR in combination with MTX or as monotherapy versus its comparators when the comparators were less effective, and it resulted in cost savings higher than £60,000 per QALY lost when SAR was less effective, except in TNFi-IR patients who are RTX eligible (where the ICER for SAR + MTX compared with RTX + MTX was £130,691 per QALY gained) and in patients with moderate RA and a DAS28 of > 4.0 (where the ICER of SAR + MTX compared with MTX was £38,254 per QALY gained). Following a critique of the model, the ERG undertook exploratory analyses after applying two changes to the company's model: (1) use of a latent class approach to model Health Assessment Questionnaire Disability Index (HAQ-DI) progression for patients on cDMARDs; and (2) amendment of the company's modelling of patient progression from moderate to severe RA. The ICERs estimated by the ERG's exploratory analyses for SAR + MTX increased to £171,466 per QALY gained when compared with RTX + MTX in TNFi-IR patients who are RTX eligible, and to £63,438 per QALY gained when compared with MTX in patients with moderate RA and a DAS28 of > 4.0. The Appraisal Committee concluded that SAR in combination with MTX or as monotherapy is a cost-effective use of NHS resources in the considered populations, except in TNFi-IR patients who are RTX eligible and in patients with moderate RA and a DAS28 of > 4.0.