Estimating the cost and health status consequences of treatment with TNF antagonists in patients with psoriatic arthritis.
OBJECTIVE
Tumour necrosis factor (TNF) has been shown to improve the outcomes in patients with psoriatic arthritis (PsA). We estimate the long-term impact on health status of prescribing the TNF antagonist etanercept, and evaluate the cost-effectiveness in a health economic model.


METHODS
The relationship between disability (Health Assessment Questionnaire) and health state utility was explored to estimate the quality-adjusted life years (QALYs) gained from the TNF antagonist etanercept. A model was then used to compare sequences of treatments for PsA after failure of two conventional disease modifying anti-rheumatic drugs (DMARDs). One arm commences on etanercept therapy and this is compared with a strategy commencing with combination therapy of methotrexate and ciclosporin and another commencing with leflunomide. Individual patient data from Phase III etanercept trials is used to populate the model supported by published evidence from extensive literature searches. By incorporating a life table specific for a PsA population, and using a number of evidence- and expert opinion-based assumptions for disease progression, the model was extended beyond the trial duration to a 10-yr time horizon. Cost offsets were produced by avoiding surgery through delayed progression; drug and monitoring costs were also modelled.


RESULTS
Over the 10 yrs, modelled etanercept treatment gave 0.82 more QALYs when compared with combination therapy with methotrexate and ciclosporin, and 0.65 more QALYs in comparison with leflunomide. This equates to a central estimate for the cost per QALY of pound28 189 and pound28 189 for ciclosporin and leflunomide, respectively. Sensitivity analyses demonstrated this could vary by as much as +/-28%.


CONCLUSIONS
With limited data currently available, the potential cost-effectiveness of etanercept in DMARD failures for adults with PsA appears encouraging. The result for other TNF antagonists will depend on how their relative efficacy and drug price compares with etanercept. A number of limitations are described and priorities for further research suggested.
Bansback
N J
NJ
Health Economics and Decision Science, School of Health and Related Research ScHARR, University of Sheffield, Regent Court, 40 Regent Street, Sheffield S1 4DA, UK. n.j.bansback@sheffield.ac.uk
Ara
R
R
Barkham
N
N
Brennan
A
A
Fraser
A D
AD
Conway
P
P
Reynolds
A
A
Emery
P
P
D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D018501:Antirheumatic Agents / Q000627:therapeutic use; D015535:Arthritis, Psoriatic / Q000188:drug therapy* / Q000191:economics; D003362:Cost-Benefit Analysis; D004185:Disability Evaluation; D004359:Drug Therapy, Combination; D000068800:Etanercept; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D007074:Immunoglobulin G / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D017059:Models, Econometric; D019057:Quality-Adjusted Life Years; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use*; D017211:Treatment Failure; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000068800:Etanercept