A systematic review of the effectiveness of adalimumab

Appendix 8
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Health Technology Assessment 2006; Vol. 10: No. 42
Existing economic evaluations: appraisal and
data extraction
TABLE 78 Choi et al., 2002 159
Authors Choi, Seeger, Kuntz
Date 2002
Type of economic evaluation Cost-effectiveness analysis
Country of origin USA
Currency used US dollars
Year to which costs apply 1999
Perspective Societal
Study population Patients with MTX-naïve RA
Intervention 1 Etanercept
Intervention 2 LEF
Intervention 3 MTX (up to 15 mg weekly)
Intervention 4 SSZ
Intervention 5 No second line agent
Source of effectiveness data Clinical trial data used: ACR20 response criteria and a weighted outcome measure of ACR
responses relative to a full weight of ACR70 responses (ACR70 response: ACR70 WR) by
calculating a weighted average of proportions achieving ACR70, ACR50 and ACR20. A
weight of 1 was assigned to ACR70, a weight of 50/70 to ACR50 and a weight of 20/70 to
ACR20
Cost data handled Yes. Direct and indirect costs were considered. Medication costs were averaged wholesale
appropriately prices and monitoring costs were based on published estimates where available. If
unavailable, costs were derived from the cost of the components recommended by ACR for
each DMARD which were summed, or by monitoring guidelines in the package insert of
leflunomide
The cost of no second-line treatment was calculated by subtracting ophthalmological
monitoring cost (once over the 6-month period) from the monitoring cost of the least
expensive DMARD costs. Monitoring costs of etanercept were assumed to be the same as
the monitoring costs of the no second-line treatment. Toxicity cost associated with MTX
therapy was estimated to be $259 (1999 prices). Toxicity cost of SSZ was assumed to be the
same as MTX. It was assumed that there were no toxicity costs for leflunomide or
etanercept
Inpatient surgical costs were included to capture potential savings associated with
improvement of RA from each option. An exponential relationship between HAQ score and
inpatient surgery costs for each treatment strategy was developed. Medical admission costs
were assumed to be largely due to toxicity of DMARDs
Indirect costs were included to capture the potential savings associated with improvement of
RA for each treatment. An HAQ indirect cost assignment was used, using the same HAQ
efficacy estimates used for the surgical costs. A linear relationship was assumed to exist
between work capacity and HAQ score to infer indirect cost savings associated with HAQ
improvement. This was based on a published cost-effectiveness analysis in a Swedish RA
population. The average wage was multiplied by work capacity achieved in each option to
estimate the cost of lost work capacity
Modelling summary A decision-analytic model was constructed and analysed using Data software (version 3.5;
TreeAge Software, Williamstown, MA, USA). The decision tree with a time-horizon of
6 months was used in the model (this was considered to represent the usual duration of
clinical trials of RA)
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