Cost effectiveness of etanercept (Enbrel) in combination with methotrexate in the treatment of active rheumatoid arthritis based on the TEMPO trial

Abstract

Objective: To estimate the cost effectiveness of combination treatment with etanercept plus methotrexate in comparison with monotherapies in patients with active rheumatoid arthritis (RA) using a new model that incorporates both functional status and disease activity.

Methods: Effectiveness data were based on a 2 year trial in 682 patients with active RA (TEMPO). Data on resource consumption and utility related to function and disease activity were obtained from a survey of 616 patients in Sweden. A Markov model was constructed with five states according to functional status (Health Assessment Questionnaire (HAQ)) subdivided into high and low disease activity. The cost for each quality adjusted life year (QALY) gained was estimated by Monte Carlo simulation.

Results: Disease activity had a highly significant effect on utilities, independently of HAQ. For resource consumption, only HAQ was a significant predictor, with the exception of sick leave. Compared with methotrexate alone, etanercept plus methotrexate over 2 years increased total costs by 14,221 euros and led to a QALY gain of 0.38. When treatment was continued for 10 years, incremental costs were 42,148 euros for a QALY gain of 0.91. The cost per QALY gained was 37,331 euros and 46,494 euros, respectively. The probability that the cost effectiveness ratio is below a threshold of 50,000 euros/QALY is 88%.

Conclusion: Incorporating the influence of disease activity into this new model allows better assessment of the effects of anti-tumour necrosis factor treatment on patients' general wellbeing. In this analysis, the cost per QALY gained with combination treatment with etanercept plus methotrexate compared with methotrexate alone falls within the acceptable range.

Figure 1

Uncertainty in the cost effectiveness estimates (acceptability curves) of a 2 or 10 year intervention with etanercept plus methotrexate in patients with active RA over 10 years. Acceptability curves are generated by Monte Carlo simulation, using individually drawn bootstrap estimates (1000 in this case) from the entire distribution of costs and utilities in the different Markov states. Different levels of willingness to pay for a QALY are defined and the probabilities of the cost effectiveness ratio falling below these different thresholds estimated. The probability that a 2 year treatment with etanercept plus methotrexate in a cohort of patients such as that included in the TEMPO trial is acceptable when the willingness to pay for a QALY is €50 000 is 88%. For a 10 year treatment, the probability is 71%. For a threshold value of €82 000, the probability is 99 and 98%, respectively.