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Cost-effectiveness analysis of vaccination against hepatitis A in travellers |
Van Doorslaer E, Tormans G, Van Damme 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 Using one of five strategies in the prevention of hepatitis A virus (HAV) consisting of either new one-step vaccines (a single dose and a booster - Havrix 1440) versus current vaccine (two doses and a booster - Havrix 720) or passive vaccination with immunoglobulin; screening for the presence of HAV antibodies plus vaccination of susceptible individuals with either Havrix 1440 or Havrix 720, compared to doing nothing.
Economic study type Cost-effectiveness analysis.
Study population Travellers from low endemic countries to high endemic destinations.
Setting Primary care. The economic study was carried out in Belgium.
Dates to which data relate The effectiveness data were extracted from studies published between 1981 and 1994. The resource use and cost data were based on a Belgian study the results of which were published in 1992 and 1993. The fiscal year was not explicitly specified.
Source of effectiveness data Effectiveness data were derived from a review of published studies.
Modelling A decision tree was used to determine the expected costs and benefits of each intervention strategy.
Outcomes assessed in the review Compliance, duration of protection, and protection rate were reported for each strategy. Sensitivity and specificity of the screening test, and the percentage of symptomatic hepatitis, the percentage ofmild, moderate, severe, and fulminanthepatitis, and relapse after mild, moderate, and severe hepatitis were among the outcomes assessed in the review.
Study designs and other criteria for inclusion in the review 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 A total of 18 studies were used as references for the outcomes assessed in the review.
Methods of combining primary studies Investigation of differences between primary studies Results of the review Protection rates varied between 90% and 99% for Havrix 720 for travellers from very low, low and moderate endemicity regions, and 95% to 99% for Havrix 1440, for travellers from very low and low endemicity regions. Passive immunisation had a protection rate of 85% for travellers from low endemicity regions. Duration of protection for the three interventions varied respectively between 1 and 10 years, (Havrix 720), 3 to 10 years (Havrix 1440) and 90 days (immunoglobulin). The compliance rate varied from 100% for dose 1, 90% for dose 2, and 60% for dose 3, for Harvix 720. For Havrix 1440 the figures were 100% and 60%, for doses 1 and 2 respectively. The compliance rate for immunoglobulin was 100% for the first dose and 50% for the following doses. Sensitivity and specificity of the screening test were 99% and 99%, respectively. The percentages of symptomatic hepatitis was 90%; the percentage ofmild, moderate, severe, and fulminanthepatitis were 50%, 30%, 19.9%, and 0.1%, respectively. Relapse rates after mild, moderate, and severe hepatitis were 9%, 7%, and 2%, respectively.
Measure of benefits used in the economic analysis The measure of benefits was infections prevented for a hypothetical cohort of 100,000 travellers over a period of 10 years.
Direct costs Costs were discounted. The resource quantities were not reported separately. The cost items were reported separately. The cost analysis covered the costs of vaccination, screening, and costs of treating different types of hepatitis. The cost data were extracted from a Belgian study the results of which were published in 1992 and 1993. The perspective adopted in the cost analysis was not explicitly specified. The date of the price data was not explicitly specified.
Indirect Costs Costs were discounted. The resource quantities were reported separately. The cost items were reported separately. The cost analysis covered the costs due to working days lost. The estimation of working days lost due to illness was based on a weighted average. The cost data were based an assumptions made by the authors. The date of the price data was not explicitly specified.
Sensitivity analysis The robustness of the study conclusions was tested in relation to the key parameters of the model using sensitivity and threshold analyses. Additionally, the results of the study were reassessed in the light of the inclusion of indirect costs.
Estimated benefits used in the economic analysis The number of infections prevented for a hypothetical 100,000 travellers over a period of 10 years compared to doing nothing was 556 for Harvix 1440, 475 for Harvix 720, 551 for screening + Harvix 1440, 470 for screening + Harvix 720, and 304 for immunoglobulins.
Cost results The discount rate was 5%. Administration of immunoglobulins resulted in the lowest incremental costs to immunize a hypothetical cohort of 100,000 travellers over a 10-year period (3,322,487) with Havrix 1440 costing 4,201,085, Havrix 720 4,830,072, Havrix 1440 plus screening 4,581,079 and Havrix 720 plus screening costing 5,056,780.
Synthesis of costs and benefits Active immunisation with Havrix 1440 has the lowest cost per case of HA prevented (7,553 compared to 10,165 for Havrix 720, 8,319 for Havrix 1440 plus screening, 10,750 for Havrix 720 plus screening, and 10,920 for immunoglobulin). Sensitivity analysis showed an increased efficiency of Havrix 1440 with increased travel frequency over 10 years and increased efficiency of screening prior to vaccination with Havrix 1440 if prevalence of antibodies to HA virus exceeds 35% in the country of origin of the traveller. Results were even more favourable to Havrix 1440 when indirect costs were included (5,488 per case prevented).
Authors' conclusions It was shown that passive immunisation remains the most cost-effective strategy for those expected to travel to high endemic areas no more than twice over the next 10 years and for short duration of stay. Routine vaccination (with the new vaccine) is always more cost-effective as soon as the travel frequency for the next 10 years is three times or more, or if the duration of one stay exceeds 6 months. For target groups with an average prevalence of immunity above 35% performing a screening test before vaccination is more cost-effective.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator was clear. Validity of estimate of measure of benefit The internal validity of the estimate of the benefit may be weakened by the apparent lack of a systematic literature review and quality assessment of the primary studies included therein. Validity of estimate of costs Resource utilization was not reported separately from the costs and adequate details of methods of cost estimation were not given. Other issues Given the lack of a systematic literature review, a quality assessment of the primary studies included in the review, and statistical analysis of the costs, the results may need to be treated with some caution. Bibliographic details Van Doorslaer E, Tormans G, Van Damme P. Cost-effectiveness analysis of vaccination against hepatitis A in travellers. Journal of Medical Virology 1994; 44(4): 463-469 Indexing Status Subject indexing assigned by NLM MeSH Cost-Benefit Analysis; Hepatitis A /epidemiology /immunology /prevention & Hepatitis A Vaccines; Hepatitis A Virus, Human /immunology; Humans; Immunization, Passive; Mass Screening; Travel; Vaccination; Viral Hepatitis Vaccines /administration & control; dosage /economics AccessionNumber 21995000439 Date bibliographic record published 31/07/1999 Date abstract record published 31/07/1999 |
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