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Cost-effectiveness modeling of abatacept versus other biologic agents in DMARDs and anti-TNF inadequate responders for the management of moderate to severe rheumatoid arthritis |
Russell A, Beresniak A, Bessette L, Haraoui B, Rahman P, Thorne C, Maclean R, Dupont D |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. CRD summary This study assessed the cost-effectiveness of abatacept for patients with moderate-to-severe rheumatoid arthritis. The authors concluded that, for patients with an inadequate response to disease-modifying anti-rheumatic drugs, abatacept was cost-effective as an initial biologic treatment or as a second biologic treatment after the failure of one anti-tumour necrosis factor drug. The methods were appropriate and reported well, but the results were reported less fully. Given the scope of the analysis, the authors' conclusions appear to be appropriate. Type of economic evaluation Cost-effectiveness analysis Study objective The objective was to assess the cost-effectiveness of abatacept compared with other biologic treatments for patients with moderate-to-severe rheumatoid arthritis and an inadequate response to one or more disease-modifying anti-rheumatic drug (DMARD) or anti-tumour necrosis factor (anti-TNF) drug. Interventions Abatacept administered intravenously over 30 minutes, at zero, two, and four weeks, then every four weeks, was compared with a successive trial of anti-TNF drugs, which included etanercept, infliximab, and adalimumab and was based on medical practice in Canada.
The treatment sequences were etanercept, infliximab, adalimumab, then DMARDs (usual care), abatacept, etanercept, infliximab, then DMARDs (first-line abatacept), and etanercept, abatacept, infliximab, then DMARDs (second-line abatacept). Methods Analytical approach:A decision-tree model was used to combine published data to assess the cost-effectiveness of the abatacept strategies versus the anti-TNF strategy. The time horizon was two years. The authors reported that the perspective was that of the public payer.
Effectiveness data:The effectiveness measures were from published pivotal trials or clinical trial analyses. The main clinical effectiveness measure was remission, which was defined by the Disease Activity Score (DAS28).
Monetary benefit and utility valuations:None.
Measure of benefit:Treatment success was defined as achieving remission, with a DAS28 of less than 2.6, or a low disease activity state (LDAS), with a DAS28 of 3.2 or less.
Cost data:The direct costs included visits to health professionals (family physicians, out-patient physicians, allied health professionals, and dentists), laboratory tests and investigations (X-ray, computed tomography, magnetic resonance imaging, ultrasound, electrocardiogram (ECG), bone density scan, and other tests), hospitalisations, prescribed drugs, home care, transport, and adaptive aids and other devices. The drug costs were calculated based on approved product monographs. The other medical costs were from 253 adult patients from the province of Ontario; 138 provided complete DAS28 data. All costs were reported in Canadian dollars (CAD).
Analysis of uncertainty:A probabilistic sensitivity analysis was undertaken by fitting probability distributions to each model parameter. Using Monte Carlo simulation, a value from each distribution was selected at random to recalculate the costs and outcomes. This process was repeated 5,000 times to obtain 95% confidence intervals. Results For patients with an inadequate response to DMARDs, first-line abatacept was dominant, as it was more effective and less costly. Compared with usual care (sequential anti-TNF therapy), it provided a 13.8% greater probability of achieving a LDAS and a cost saving of CAD 730 or a 9.6% greater probability of achieving remission and a cost saving of CAD 504.
Second-line abatacept, compared with usual care, provided a 3.7% greater probability of achieving a LDAS at a cost of CAD 463 or a 3.5% greater probability of remission at a cost of CAD 589. This produced an incremental cost-effectiveness ratio of CAD 12,514 per additional LDAS, or CAD 16,829 per additional remission.
For patients with an inadequate response to DMARDs and one anti-TNF agent, compared with second-line usual care, second-line abatacept provided a 6.9% greater probability of achieving a LDAS and 3.5% greater probability of achieving remission. The incremental cost-effectiveness ratios were CAD 20,377 per additional LDAS or CAD 26,400 per additional remission. Authors' conclusions The authors concluded that, for patients with an inadequate response to DMARDs, abatacept was cost-effective as an initial biologic treatment or as a second biologic treatment after the initial failure of one anti-TNF agent. CRD commentary Interventions:The interventions were adequately reported and appear to have been appropriate comparators. Justifications were given for the inclusion and exclusion of comparators.
Effectiveness/benefits:The effectiveness estimates were from numerous randomised trials, and the internal validity of the model is likely to have been high. The authors did not report a systematic review to identify these trials, making it unclear if all the relevant evidence was included. The outcome measures for the cost-effectiveness analysis (remission and LDAS) were specific to rheumatoid arthritis, and could hamper comparisons with other interventions for other diseases.
Costs:The perspective was explicitly reported and it appears that all those cost categories and costs relevant to the payer perspective were analysed. The authors reported the sources for the unit costs and resource quantities. The time horizon was two years, but the authors did not report any discounting. The price year was not explicitly reported, which will hamper any future inflationary exercises.
Analysis and results:The evidence was appropriately combined in a decision-tree model. Details of the model were provided, including a diagram. The impact of uncertainty was tested, in a probabilistic sensitivity analysis, which should have given a good indication of the overall model uncertainty. The methods of the analysis were reported well, but the results could have been reported in more detail. For example, the authors did not report the 95% confidence intervals, nor the probability that the intervention would be cost-effective at a particular cost-effectiveness threshold. The main limitation was reported to be that comparing across clinical trials was difficult as their populations and methods were not always similar.
Concluding remarks:The methods were appropriate and they were reported well, but the results could have been given in more detail and the measure of benefit might restrict the generalisability of the study. Given the scope of the analysis, the authors' conclusions appear to be appropriate. Funding Funded by Bristol-Myers Squibb International, manufacturer of abatacept. Bibliographic details Russell A, Beresniak A, Bessette L, Haraoui B, Rahman P, Thorne C, Maclean R, Dupont D. Cost-effectiveness modeling of abatacept versus other biologic agents in DMARDs and anti-TNF inadequate responders for the management of moderate to severe rheumatoid arthritis. Clinical Rheumatology 2009; 28(4): 403-412 Indexing Status Subject indexing assigned by NLM MeSH Abatacept; Antirheumatic Agents /economics /pharmacology; Arthritis, Rheumatoid /drug therapy; Cost-Benefit Analysis; Drug Costs; Humans; Immunoconjugates /economics /pharmacology; Middle Aged; Models, Theoretical; Remission Induction; Time Factors; Treatment Outcome; Tumor Necrosis Factor-alpha /metabolism AccessionNumber 22009101096 Date bibliographic record published 09/09/2009 Date abstract record published 21/12/2011 |
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