Background Tocilizumab (TCZ) is indicated for the treatment of adult rheumatoid arthritis (RA) that has responded inadequately to one or more disease-modifying antirheumatic drugs (“DMARD-IR patients”). Whilst typically given with methotrexate (MTX), TCZ may also be administered as monotherapy in patients who are intolerant of or contraindicated to MTX. The cost-effectiveness of this approach compared with current standard care in MTX-intolerant/contraindicated DMARD-IR patients has not previously been undertaken.
Methods An economic model was developed to reflect the healthcare system and treatment pathway in Scotland. In the model, disease severity is represented by HAQ score; a surrogate health outcome which can be translated to utility scores and ultimately QALYs. The model captures the progression of HAQ score for each individual patient in an individual simulation process. ACR response rates are used as a measurement of response to treatment as these are readily available from TCZ trials as well as from RCTs of the other therapies included in this model.
Benefits were expressed as quality adjusted life years (QALYs). Costs were calculated from a National Health Service Scotland and Personal Social Services perspective and included treatment costs as well as patient-condition-related costs. The analysis calculated incremental costs and benefits associated with the addition of TCZ in first line to the standard care pathway involving certolizumab pegol, etanercept and adalimumab. Treatment effects for TCZ monotherapy were based on efficacy data from the ACT-RAY trial (Dougados et al 2011). Data from comparator medicines were sourced from available monotherapy trials of adalimumab (van de Putte et al 2004), certolizumab pegol (Fleischmann et al 2009), and etanercept (Moreland et al 1999).
Results Base case results estimated incremental costs of about £24,000 and incremental QALYs of 0.88. The incremental cost-effectiveness ratio (ICER) was £27,000 per QALY gained. The model was most sensitive to patient weight (which drives drug cost) and the parameters used in the HAQ-to-utility estimation equation.
A probabilistic sensitivity analysis produced a very similar ICER of £27,500 per QALY gained.
Conclusions The results of this analysis suggest that TCZ monotherapy represents an efficacious and cost-effective addition to the current standard of care in Scotland, for treating RA patients who are MTX intolerant.
Disclosure of Interest C. Gibbons Employee of: Roche Products Limited, A. Diamantopoulos Consultant for: Roche Products Limited, H. Pang Employee of: Roche Products Limited, C. Huertas Employee of: Roche Products Limited, F. Dejonckheere Employee of: F.Hoffmann-La Roche