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Cost effectiveness of hepatitis A prevention in France |
Severo C A, Fagnani F, Lafuma A |
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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 Recombinant hepatitis A virus (HAV) vaccine ("Havrix", SmithKline Beecham).
Type of intervention Primary prevention and screening.
Economic study type Cost-effectiveness analysis.
Study population Closed population cohort for 3 risk groups: young men doing alternative military service in developing countries, four types of hospital personnel and tourists visiting highly endemic countries.
Setting Primary care and hospital. The economic study was carried out in France.
Dates to which data relate The main effectiveness data were taken from sources dated 1990-94. Resource use and cost data were mainly derived from structured interviews, published studies, and on-line database from the years 1970, 1991, and 1994. The price year was 1993.
Source of effectiveness data Modelling A decision model was used to calculate costs and benefits associated with the strategies during a 10-year period. The model incorporated epidemiological and demographic data from France.
Methods used to derive estimates of effectiveness Estimates of effectiveness of the prevention technologies were derived from experts' opinion, structured interviews and authors' assumptions. The assumed screening test accuracy was based on evidence from one published study.
Estimates of effectiveness and key assumptions The sensitivity and specificity of the screening test for HAV seroprevalence were both assumed to be 99%. For the recombinant HAV vaccine, the effectiveness was assumed to be 98-99%. Passive immunisation with gammaglobulin had an effectiveness rate of 39%.
Measure of benefits used in the economic analysis The measure of benefits was the number of symptomatic cases avoided for each target group.
Direct costs Some quantities of resource use were reported separately from the costs. The total average cost of HAV detection tests, average cost of illness (including diagnosis and follow up) and the average cost of hospital care were included. A discount rate of 5% was applied. The quantity/cost boundary adopted was the hospital and the patient. A model was used in estimating total costs for each target group, under the corresponding payer's perspective. Costs were taken from French studies published in 1990-94. The price year was 1993.
Indirect Costs The quantities of resource use were reported separately from the costs. Productivity losses for active salaried tourists and hospital workers were included in the estimates. The price year was 1993. The data were obtained from previously published information relating to France.
Sensitivity analysis The main costs variables and parameters were tested by one-way simple sensitivity analysis. Threshold analysis was used to identify the age above which 'screening and vaccination' became the optimal strategy in military volunteers.
Estimated benefits used in the economic analysis Assuming 100% compliance in 4,450 military volunteers, the screening and vaccination strategy was expected to prevent 1,691 new cases in 10 years (out of 1,717 cases without prevention); gammaglobulin and systematic vaccination would prevent, respectively, 662 and 1,706 cases of HAV infection. In 865,500 French adult tourists (again, given 100% compliance), the screening and vaccination strategy would prevent 3,245 cases, while systematic vaccination would prevent 3,278 cases of HAV infection (out of 3,281 cases under no prevention). In 808,500 French hospital workers, screening and vaccination and systematic vaccination would prevent 4,436 and 4,391 cases of HAV infection, respectively (out of 4,440 cases under no prevention and assuming a 100% compliance).
Cost results Assuming 100% compliance, costs were calculated for each target group.
In the military volunteers, the screening andvaccination and the systematic vaccination options would produce savings in direct medical costs of FF4.2 and FF4.7 million, respectively, compared with no prevention over a 10-year period. Gammaglobulin would result in an additional FF2.89 million relative to 'no prevention'.
In tourists, screening and vaccination would generate FF802.26 and FF0.01 million in direct and indirect costs, respectively. Systematic vaccination turned out to be associated with figures of FF505.11 and FF0.09 million, respectively. 'No prevention' would be expected to generate FF10.47 and FF9.01 million, respectively.
In hospital workers the 'screening strategy' would be roughly half as costly as systematic vaccination (direct costs, FF 261.7 million versus FF449.19 million). Indirect costs were relatively small (less than FF0.25 million in both cases). 'No prevention' resulted in direct costs of FF16.34 million and indirect costs of FF 24.58 million.
Synthesis of costs and benefits The cost effectiveness ratios (CERs), cost per case avoided, were calculated for each target group, using 1993 prices and a 5% annual discount rate. This estimate was not stated because systematic vaccination turned out to be the 'dominant strategy', whilst vaccination (both strategies) was a dominant strategy against gammaglobulin and 'no prevention'.
In tourists the CERs of vaccination strategies were FF 177.612, for screening and vaccination, and FF281.463, for systematic vaccination.
In the hospital workers the CER for screening with vaccination was calculated to be 45% lower than that for systematic vaccination (FF 65.108 versus FF113.715). The results vary relatively little when indirect costs are included. Sensitivity analyses showed the results to be robust against most changes in baseline values of relevant parameters. However, variation in compliance rates and age-specific prevalence and incidence rates had effects of 57% or more upon the base case CERs. Screening and vaccination became the optimal strategy for French military volunteers aged 31 years and older.
Authors' conclusions The cost effectiveness of vaccination against HAV varies greatly depending upon the average seroprevalence of the target group and the duration and intensity of the risk to which they are exposed.
CRD Commentary No clear justification was provided for the choice of prophylaxis with gammaglobulin as comparator. Indeed the authors reported that it is seldom used for the context in question. The use of the recombinantvaccine "Havrix" is not supported by clear evidence of its long-term effectiveness. Therefore, further studies are required to support the assumptions implicit in this study regarding the long-term effectiveness of the recombinant hepatitis A vaccine. Provided these assumptions are valid, the generalisability of the study results would depend mainly on the applicability of French age-specific immunoseroprevalence and incidence of HAV-infection relations to other countries or regions in Europe and North America. Adequate details were given of the sources of estimates, of resource use and prices and the price date. Appropriate comparisons were made with other studies conducted in Great Britain and France, which presented evidence supporting the study results. The conclusions were justified given the uncertainties in the data (sensitivity analysis).
Source of funding Supported by SmithKline Beecham, France.
Bibliographic details Severo C A, Fagnani F, Lafuma A. Cost effectiveness of hepatitis A prevention in France. PharmacoEconomics 1995; 8(1): 46-61 Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Cost-Benefit Analysis; Decision Theory; Developing Countries; Female; France /epidemiology; Hepatitis A /economics /epidemiology /prevention & Hepatitis Antibodies /analysis; Humans; Immunization, Passive /economics; Male; Mass Screening /economics; Personnel, Hospital; Risk; Travel; Vaccines, Synthetic /economics; Viral Hepatitis Vaccines /economics; control AccessionNumber 21995000838 Date bibliographic record published 14/08/1998 Date abstract record published 14/08/1998 |
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