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Economic evaluation of screening strategies for chronic hepatitis C |
Loubiere S, Rotily M, Portal I, Bourliere M, Moatti J P |
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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 The health technologies considered were screening and treatment strategies for hepatitis C in populations at different risk of infection. Five screening strategies were analysed: PCR (polymerase chain reaction), ELISA, ELISA followed by ELISA if tested positive, ELISA followed by RIBA if tested positive and two ELISA tests in parallel. Two treatment strategies were analysed.
With the first strategy (H1), after a positive diagnosis patients who had never been treated received interferon for 12 months while patients who have relapsed received a combination of interferon and ribavirine for 6 months.
In the second treatment strategy, patients who had never been treated received 12 months of interferon and ribavirine and patients who had relapsed received 6 months of interferon and ribavirine.
These screening and treatment strategies were compared to a status quo option that consisted of having no screening policy for hepatitis C.
Type of intervention Screening, diagnosis and treatment.
Economic study type Cost-effectiveness analysis.
Study population Three study populations, at different levels of risk of infection, were considered: intravenous drug users (IVDU), recipients of blood transfusion before 1991 (transfused), and the general population. The prevalence of hepatitis C virus was estimated at 80% for IVDU, 7% for the transfused and 1.2% for the general population. It was assumed that infected patients, diagnosed early through screening, would be treated at an earlier stage of the disease than if they had not been diagnosed (15% of minor hepatitis, 65% of chronic hepatitis and 15% of cirrhosis).
Setting The setting was not specified, as the population studied was hypothetical, but it was indicated that the screening could take place either in primary or secondary care settings. The economic study was carried out in France.
Dates to which data relate The effectiveness data were collected from publications dated from 1992 to 1998. The dates for the resource use data were not reported. The price year was not reported.
Source of effectiveness data The evidence and estimate for final outcomes was based on a review of published studies.
Modelling A decision analysis model, incorporating a Markov chain (Data 3.5), was used to estimate the costs and benefits of the different screening and treatment strategies.
Outcomes assessed in the review The outcomes assessed in the review were the prevalence of the hepatitis C virus in the IVDU, transfused, and general populations, all cause mortality, transitions between disease states due to the virus, the sensitivity and specificity of the screening tests, and effectiveness of treatment with ribavirine and interferon.
Study designs and other criteria for inclusion in the review The study designs and other criteria for inclusion in the review were not specified.
Sources searched to identify primary studies The sources searched to identity primary studies were not specified.
Criteria used to ensure the validity of primary studies The criteria used to ensure the validity of primary studies were not specified.
Methods used to judge relevance and validity, and for extracting data These criteria were not specified.
Number of primary studies included At least 15 primary studies were included in the review.
Methods of combining primary studies The results of the individual primary studies were combined using a narrative method.
Investigation of differences between primary studies The authors did not investigate the difference between primary studies.
Results of the review The prevalence of the hepatitis C virus in the IVDU population was 80%, 7% in the transfused population and 1.2% in the general population.
All cause mortality was 0.91% per year in the general population and 1% in the IVDU population.
The annual transition rate from infection to remission was 20%, 80% from chronic hepatitis to infection, 0.2% from chronic hepatitis to spontaneous remission, 5.9% from chronic hepatitis to cirrhosis, 4% from cirrhosis to decompensated cirrhosis, 3% from decompensated cirrhosis to cancer, 5% from decompensated cirrhosis to transplant, 10% from decompensated cirrhosis to death, 80% from cancer to death and 6.9% from transplant to death.
The sensitivity and specificity of the screening tests were:
ELISA, sensitivity 99% and specificity 90%;
RIBA, sensitivity 98% and specificity 95%;
PCR, sensitivity 99.9% and specificity 99.3%.
The effectiveness of treatment with ribavirine and interferon were not reported.
These data were used as the principal input parameters for the model.
Measure of benefits used in the economic analysis The outcome measures used in the analysis were the number of chronic hepatitis cases, severe pathologies (such as cancer and cirrhosis), and deaths avoided due to screening and treatment compared to the status quo policy.
Direct costs Costs were discounted at 3%, which was appropriate since costs were incurred over a period of time greater than 2 years. Quantities and costs were not reported separately. Costs included cost of diagnostic testing, cost of a medical consultation with screening, costs of additional testing, costs of treatment, cost of medical follow-up of patients at each stage of disease including hospital costs, and costs associated with diagnostic errors (false positives). It was not clear how quantities were estimated. Costs were derived using the decision analytic model. The source of quantities was not reported. The source of the costs was a published study. The dates when the quantity of resources was measured were not reported. The price year was not reported.
Statistical analysis of costs No statistical analysis of costs was carried out.
Indirect Costs Indirect costs were not included in the analysis.
Sensitivity analysis Sensitivity analyses were not carried out.
Estimated benefits used in the economic analysis Under the H1 treatment strategy, the number of avoided cases of severe chronic hepatitis (SCH) varied from 40,096 to 41,037 in the IVDU group, from 6,786 to 6,988 in the transfused group and from 144,153 to 147,528 in the general population.
The number of severe pathologies (SP) avoided varied from 7,360 to 7,533 in the IVDU group, from 1,253 to 1,283 in the transfused group and from 26,460 to 27,080 in the general population.
The number of deaths avoided varied from 2,773 to 2,838 in the IVDU group, from 472 to 483 in the transfused group and from 9,968 to 10,202 in the general population.
Under the H2 treatment strategy, the number of avoided cases of SCH varied from 58,538 to 59,911 in the IVDU group, from 9,969 to 10,202 in the transfused group and from 210,454 to 215,383 in the general population.
The number of SP avoided varied from 8,738 to 8,943 in the IVDU group, from 1,488 to 1,523 in the transfused group and from 31,149 to 32,117 in the general population.
The number of deaths avoided varied from 3,139 to 3,213 in the IVDU group, from 534 to 547 in the transfused group and from 11,287 to 11,551 in the general population.
The length of follow-up was 10 years. Side effects of treatment were not included in the analysis due to the lack of available data.
Cost results Under H1, the total discounted costs (in billions of francs) varied from 5,819 to 5,957 for the IVDU group, from 1,820 to 2,015 in the transfused group and from 31,251 to 40,737 in the general population.
Under H2, the total discounted costs (in billions of francs) varied from 7,971 to 8,158 for the IVDU group, from 2,935 to 3,152 in the transfused group and from 38,341 to 47,965 in the general population.
With maintenance of the current policy of no screening, the cost in the IVDU population was Ffr 13,008 billion, Ffr 4,980 billion in the transfused population and Ffr 46,342 billion in the general population.
The duration of follow-up was 10 years.
Synthesis of costs and benefits Benefits and costs were combined into average and marginal cost-effectiveness ratios representing the cost per case avoided.
Under the H1 strategy, average cost-effective ratios varied from 144,273 to 145,187 for the IVDU group, from 265,515 to 290,156 in the transfused group and from 215,917 to 276,172 in the general population.
Under the H2 strategy, average cost-effective ratios varied from 135,547 to 136,173 for the IVDU group, from 293,294 to 308,967 in the transfused group and from 181,451 to 222,723 in the general population.
The authors reported that ELISA followed by another ELISA test was the most cost-effective alternative.
Authors' conclusions The status quo policy was dominated whatever screening strategies were considered. The strategy consisting of an ELISA test confirmed by another ELISA test was the best strategy in terms of cost-effectiveness. To screen and treat with interferon and ribavirine was a better option than adding ribavirine only for relapse patients.
CRD COMMENTARY - Selection of comparators A justification was given for the choice of screening strategies and treatments, namely that they represented currently available health technologies in the authors' setting. The comparison with a "do nothing" strategy was justified as this is the current policy in France. You, as a user of this database, should decide whether these health technologies are widely used in your own setting.
Validity of estimate of measure of effectiveness The measures of effectiveness used in the model were well reported in general, with the exception of the efficacy of both treatment options. The effectiveness estimates were combined using a narrative method, which seems appropriate for the study question. However, the authors provided few details on how the literature review had been undertaken, which criteria had been used to select studies and to extract data and how differences between primary studies had been dealt with. The lack of sensitivity analysis also limits the validity and generalisability of the results.
Validity of estimate of measure of benefit Health benefits, measured as number of cases avoided, were modelled using a decision analysis model, which incorporated changes in health states (Markov), and this was appropriate for the study. The authors discussed the lack of data concerning the quality of life of patients with hepatitis C and justified their choice of health benefit measure.
Validity of estimate of costs In general, the costing was well conducted. All categories of cost relevant to the perspective adopted were included in the analysis, with the exception of the fixed costs of putting a screening policy into place. No relevant costs appear to have been excluded from the analysis. Discounting was conducted appropriately. Unit costs were reported. However some weaker aspects of the costing were that quantities were not reported separately from costs and their source was unclear. No sensitivity analyses were conducted on costs or resource use and the price year was not reported. These features limit reflation exercises to other settings.
Other issues The authors made appropriate comparisons of their findings with those from other studies but did not address the issue of generalisability to other settings. The authors did not present their results selectively. The study looked at different sub groups at risk of infection and this was reflected in their conclusions. The authors discussed some possible limitations to their study. First, long term effects of treatments and the effects on patients who are not responding to treatment are still uncertain and assumptions had to be made for the model. Second, the data concerning the sensitivity and specificity of diagnostic tests are still uncertain. Third, the lack of data on patients' quality of life prevented the measurement of benefits in quality-adjusted life years. Fourth, the fixed costs of implementing a screening policy were not included in the costing.
Implications of the study The authors recommend implementing a screening and treatment strategy for hepatitis C based on a single ELISA followed by a second ELISA test.
Source of funding Funded by Produits Roche and le conseil regional PACA.
Bibliographic details Loubiere S, Rotily M, Portal I, Bourliere M, Moatti J P. Economic evaluation of screening strategies for chronic hepatitis C. Medecine et Maladies Infectieuses 1999; 29(5): 337-344 Indexing Status Subject indexing assigned by CRD MeSH Chronic Disease; Cost-Benefit Analysis; Decision Support Techniques; Decision Trees; Disease Transmission, Infectious; France; Hepatitis C /prevention & Mass Screening /economics /methods; Seroepidemiologic Studies; control /economics AccessionNumber 22000001257 Date bibliographic record published 30/06/2002 Date abstract record published 30/06/2002 |
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