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Hepatitis C: an economic evaluation of extended treatment with interferon |
Shiell A, Brown S, Farrell G C |
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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. Health technology Extension of treatment with interferon alpha (IFa) for hepatitis C infection.
Economic study type Cost-effectiveness study.
Study population A hypothetical cohort of 1,000 patients, aged 40 years at the start of treatment, with chronic HCV infection.
Setting Secondary care (hospital). The study was conducted in Australia.
Dates to which data relate The effectiveness data were derived from studies published between 1994 and 1997. All costs are in Australian dollars at 1996 prices.
Source of effectiveness data The effectiveness data were derived from a published meta-analysis of the effectiveness of IFa treatment, professional judgement about treatment protocols and a literature search for quality-of-life weights.
Modelling A decision-analytic method (Markov model) was used to simulate the costs and effects of a six-month and a twelve-month period of IFa treatment versus no treatment. Both costs and effects were modelled over 30 years.
Outcomes assessed in the review The outcomes assessed in the review were the effectiveness of the treatment, the rates of progression from one stage to another for HCV infection, the quality of life and its weights.
Study designs and other criteria for inclusion in the review The authors used their previous study on the cost-effectiveness of a six-month treatment period of chronic hepatitis C, as well as several studies which have evaluated benefits of extended treatment over twelve months rather than six.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included 6 primary studies were included.
Methods of combining primary studies Primary studies were combined using a narrative method based on clinical interpretations for two IFa treatment schemas.
Investigation of differences between primary studies Results of the review Concerning the effectiveness of IFa treatment, the long term response after 6 months' treatment was 18%, the long term response after 12 months' treatment was 35%, the treatment discontinuation rate after 12 weeks was 26%. Disease transition probabilities were 20% from chronic infection to cirrhosis, 20% from cirrhosis to advanced liver failure and 14% from cirrhosis to hepatocellular carcinoma. The health state weights were: 0.95 for chronic infection, 0.75 for cirrhosis, 0.25 for advanced liver failure and hepatocellular carcinoma, 0.95 for IFa treatment and 1.00 for resolved infection.
Measure of benefits used in the economic analysis The measures of benefit, as determined by the model, were the number of discounted life-years saved and the number of QALYs gained.
Direct costs Direct costs included costs of the medical management of chronic infection, the cost of IFa treatment, weighted costs for the treatment of the main clinical manifestations of cirrhosis and the cost of the terminal care. The boundary adopted was therefore the healthcare system. Costs and quantities were reported separately and discounting was applied to both effects and costs.
Statistical analysis of costs Currency Australian dollars (Aus$).
Sensitivity analysis A sensitivity analysis was carried out on response rates, rates of disease progression, time to develop sequelae, costs of treatment, percentage of patients excluded at 12 weeks, age groups, the discount rate, and the adjustment for quality of life.
Estimated benefits used in the economic analysis Compared with no treatment, the treatment with IFa for 6 months resulted in 94.2 additional discounted life-years gained and 320.1 additional discounted QALYs gained in a cohort of 1,000 patients. Extending treatment from 6 to 12 months resulted in 89.0 additional discounted life-years gained and 170.8 additional discounted QALYs gained.
Cost results Net costs of 6 and 12 months' treatment with IFa were estimated to be Aus$1,800 per patient and Aus$3,694 per patient respectively after discounting at 3%.
Synthesis of costs and benefits Incremental costs were reported. A 6 month treatment period resulted in an incremental cost per life-year saved of Aus$19,110 and per QALY gained of Aus$5,625. Extending treatment from 6 to 12 months resulted in an incremental cost of Aus$15,835 per life-year saved and Aus$8,250 per QALY gained. Concerning the sensitivity analysis, the choice of discount rate and weights for quality of life had an effect on incremental costs, and, in addition, extension of treatment for another 6 months was sensitive to changes in rates of disease progression and treatment effectiveness.
Authors' conclusions The authors concluded that the cost-effectiveness of IFa treatment for HCV infection has improved as a result of better patient selection, cost reductions and enhanced effectiveness of extended treatment. The results are sensitive to assumptions made about quality of life and the discount rate. Further research is needed to examine the personal and social impact of HCV infection and the utility of its treatment.
CRD COMMENTARY - Selection of comparators The rationale for the choice of comparator is clear.
Validity of estimate of measure of benefit The estimate of the measure of benefit in the economic analysis was based on a modelling approach using assumptions for values and costs derived from previous published studies. The literature search strategy was not provided and the effectiveness results were based on a recently published meta-analysis.
Validity of estimate of costs Although resource quantities were reported separately from prices, inadequate details of methods of quantity and cost estimation were given. The authors only subjected the cost of treatment to sensitivity analysis and did not consider side-effects associated with treatment, or other indirect costs, although they may be substantial.
Other issues The authors' conclusions were justified within the well accepted limitations of simulation models. The absence of threshold values for the incremental cost weakens the generalisability of the results.
Implications of the study The authors' conclusions that the cost-effectiveness of IFa treatment for hepatitis C infection has improved may need to be supported by a more appropriate long-term investigation based on a prospective study.
Bibliographic details Shiell A, Brown S, Farrell G C. Hepatitis C: an economic evaluation of extended treatment with interferon. Medical Journal of Australia 1999; 171(4): 189-193 Indexing Status Subject indexing assigned by NLM MeSH Antiviral Agents /economics /therapeutic use; Australia; Cost-Benefit Analysis; Decision Support Techniques; Hepatitis C, Chronic /drug therapy /economics; Humans; Interferon-alpha /economics /therapeutic use; Markov Chains; Quality of Life; Quality-Adjusted Life Years AccessionNumber 21999001602 Date bibliographic record published 31/05/2000 Date abstract record published 31/05/2000 |
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