| Sumario: | Background: Treatment with tumour necrosis factor alpha (TNF-α, or simply TNF) inhibitors is considered to be an alternative to the use of traditional disease-modifying anti-rheumatic drugs (DMARDs) in patients with different rheumatic diseases, i.e. rheumatoid arthritis (RA). There are three TNF-inhibitor drugs currently available on the market (brand names in brackets): adalimumab (Humira), etanercept (Enbrel) and infliximab (Remicade). The Norwegian Knowledge Centre for the Health Services has previously summarised the evidence on the drugs' efficacy and safety (in randomised clinical trials and observational studies) while the present report considers cost-effectiveness of the drugs for rheumatoid arthritis. After considerable growth over several years, the aggregate sales of the three drugs amounted to 860 million NOK in 2006. RA is a serious disease, not least from an economic perspective. No cost-of-illness studies have been found for Norway, but studies from Sweden suggest that the costs of the disease are substantial with a large proportion related to loss of work capacity. Methods: We undertook a review of economic evaluations of TNF-inhibitors against RA, and considered an analysis of health-related quality of life data for patients on TNF-inhibitors and DMARD users from a Norwegian observational study. Results: A total of twelve studies from six countries were included in the literature review. The studies were based on health economic models, which were diverse in their characteristics, and therefore the estimates of cost-effectiveness varied significantly. Conclusions: In our review of economic evaluations of TNF-inhibitors, we found significant variation in the type and features of the models used, which led to a wide range of estimates. The potential for direct comparisons of results between the studies, and thus transferability of results into Norwegian setting, is limited. With this in mind, our main conclusions are as follows:1. First line therapy: TNF inhibitors seem not to be cost-effective as first line therapy, based on the one study in which this was considered.2. Second line therapy: We cannot draw any conclusions, since no relevant studies were found.3. Third line therapy: TNF-inhibitors may be cost-effective, particularly in the case of patients in early disease. The drugs are also likely to be more cost-effective for patients who experience a good rather than a moderate response.4. Indirect costs: Prevention of productivity loss may account for considerable savings, but has only been accounted for in a few of the economic evaluations.
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