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Active versus passive immunization against hepatitis A in the Israel defence forces: a cost-benefit analysis |
Gillis D, Yetiv N, Gdalevich M, Mimouni D, Ashkenazi I, Shpilberg O, Eldad A, Shemer J |
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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 use of immune serum globulin (ISG) prophylaxis and inactivated hepatitis A vaccine (iHAV) against hepatitis A.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised the Israeli army. In particular, six groups of soldiers were considered:
group 1 comprised male soldiers in field units serving 3 years in comparatively crowded and low-hygiene conditions;
group 2 comprised female conscripts in field units serving 2 years in conditions similar to group 1;
group 3 comprised both genders, standing army members in field units and serving an average of 20 years in conditions as above;
groups 4, 5 and 6 included soldiers of the respective categories as for groups 1 (male), 2 (female), and 3 (both genders) serving in non-field units, in other words, close to home in relatively good hygiene conditions.
Setting The setting was the community (army life). The economic study was carried out in Israel.
Dates to which data relate The dates for the effectiveness or resource use data were not reported. No price year was reported.
Source of effectiveness data The effectiveness data were derived from the authors' assumptions.
Methods used to derive estimates of effectiveness The effectiveness data were derived from the authors' assumptions, which were based on both internal data and published studies.
Estimates of effectiveness and key assumptions The authors assumed the following:
iHAV would be given only to hepatitis A antibody-negative soldiers, about 61.6% (95% confidence interval: 57.6 - 65.6) of Israel Defence Force recruits after universal testing;
the attack rates ranged from a minimum of 60 per 10,000 to a maximum of 200 per 10,000 in field units, and from 20 per 10,000 to 60 per 10,000 in non-field units; and
the programme efficacy was 85% for ISG and close to 100% for iHAV.
Measure of benefits used in the economic analysis The benefit measure used in the economic analyses was the number of expected cases of hepatitis A per 10,000 soldiers per year. This came from the effectiveness study (authors' assumptions).
Direct costs Discounting was not applied and the time horizon of the study was not reported. The economic analysis estimated the total costs of the prevention programme and the total savings from disease prevention. The ratio between these two led to the cost-benefit ratio. The health service costs included in the analysis were for vaccination, equipment, personnel, and the serological test (for iHAV only). The costs associated with side-effects of the vaccine were considered negligible and were not included in the analysis. The unit costs were reported separately from the quantities of resources used. The cost/resource boundary adopted in the study was not explicitly stated, but is likely to have been that of the patient's insurance company. The source of the cost data was not reported. No price year was given.
Statistical analysis of costs The costs were treated deterministically.
Indirect Costs The indirect costs were not included in the analysis.
Sensitivity analysis No sensitivity analyses were conducted.
Estimated benefits used in the economic analysis The number of expected cases per 10,000 soldiers per year was 200 in groups 1 through 3, and 60 in groups 4 through 6 for both iHAV and ISG, based on a high expected incidence of 200/10,000 or 60/10,000 for field units and non-field units, respectively; and
60 in groups 1 through 3 and 20 in groups 4 through 6 for both iHAV and ISG, based on a low expected incidence of 60/10,000 or 20/10,000 for field units and non-field units, respectively.
Cost results The costs per vaccinated soldier were:
$403.8 in group 1, $605.7 in group 2, $60.57 in group 3, $1,346 in group 4, $2,019 in group 5, and $201.9 in group 6 for iHAV, based on a high expected incidence of 200/10,000 or 60/10,000 for field units and non-field units, respectively;
$1,346 in group 1, $2,019 in group 2, $201.90 in group 3, $4,038 in group 4, $6,057 in group 5, and $605.70 in group 4 for iHAV, based on a low expected incidence of 60/10,000 or 20/10,000 for field units and non-field units, respectively;
$243.2 in groups 1, 2, and 3, $173.5 in group 4, $247.1 in group 5, and $48.53 in group 4 for ISG, based on a high expected incidence of 200/10,000 or 60/10,000 for field units and non-field units, respectively; and
$810.78 in groups 1, 2, and 3, $520.59 in group 4, $741.18 in group 5, and $145.59 in group 4 for ISG, based on a low expected incidence of 60/10,000 or 20/10,000 for field units and non-field units, respectively.
The cost-savings were either $320 or $3,240, depending on whether the soldier was a conscript or a member of the standing army.
Synthesis of costs and benefits For ISG, the cost-effectiveness ratios for maximum and minimum incidences of the disease were, respectively, $243.2 and $810.78 in groups 1, 2, and 3, $173.5 and $520.59 in group 4, $247.1 and $741.18 in group 5, and $48.53 and $145.59 in group 6.
For iHAV, the cost-effectiveness ratios for maximum and minimum incidences of the disease were, respectively, $403.8 and $1,346 in group 1, $605.7 and $2,019 in group 2, $60.57 and $201.9 in group 3, $1,346 and $4,038 in group 4, $2,019 and $6,057 in group 5, and $201.9 and $605.7 in group 6.
For ISG, the cost-benefit ratios for maximum and minimum incidences of the disease were, respectively, 0.76 and 2.533 in groups 1 and 2, 0.075 and 0.250 in group 3, 0.542 and 1.627 in group 4, 0.772 and 2.316 in group 5, and 0.015 and 0.045 in group 6.
For iHAV, the cost-benefit ratios for maximum and minimum incidences of the disease were, respectively, 1.262 and 4.206 in group 1, 1.893 and 6.309 in group 2, 0.019 and 0.062 in group 3, 4.206 and 12.619 in group 4, 6.309 and 18.928 in group 5, and 0.062 and 0.187 in group 6.
Authors' conclusions Inactivated hepatitis A vaccine (iHAV) was cost-effective only in group 1 soldiers (male soldiers in field units serving 3 years in comparatively crowded and low-hygiene conditions). Immune serum globulin (ISG) was the most cost-effective strategy for the remaining groups of soldiers. Disease incidence represented a crucial variable.
CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparators was clear. The authors stated that ISG had previously been administered to Israel Defence Forces, while iHAV represented a new product for hepatitis A prophylaxis. You should decide whether they represent valid comparators in your own setting.
Validity of estimate of measure of effectiveness The analysis of the effectiveness was based on the authors' assumptions, which were partly derived from published studies and partly from the authors' experiences. However, few details were provided. These assumptions were not investigated in sensitivity analyses, and only the impact of variations in disease incidence was analysed. The use of assumptions may represent a limitation to the internal validity of the analysis.
Validity of estimate of measure of benefit The benefit measure was calculated on the basis of the assumptions made in the effectiveness study. Thus, its reliability depends on these assumptions (see comments in previous section).
Validity of estimate of costs The perspective adopted in the study was not explicitly stated. The process used to derive the expected costs and expected cost-savings was reported in detail in an appendix to the paper. The unit costs were reported separately from the quantities of resources. However, no price year was given, thus hindering reflation exercises in other settings. The costs were treated deterministically and no sensitivity analyses were conducted. The cost estimates used in the economic analysis were specific to the study setting. The source of the cost data was unclear.
Other issues The authors made some comparisons of their findings with those from other studies. However, they did not address the issue of the generalisability of the study results to other settings. The external validity of the analysis is likely to have been low as no sensitivity analyses were conducted. The authors noted that some potential hidden benefits related to vaccination were not included in the analysis. The study referred to a hypothetical sample of soldiers, but the authors stated that the benefits of the vaccination programme could also affect the civilian population (due to contacts between army personnel and civilians).
Implications of the study The authors highlighted the fact that reductions in the cost of iHAV may be possible in the near future. This would lead to improved cost-effectiveness of such a vaccine strategy for most soldier groups.
Bibliographic details Gillis D, Yetiv N, Gdalevich M, Mimouni D, Ashkenazi I, Shpilberg O, Eldad A, Shemer J. Active versus passive immunization against hepatitis A in the Israel defence forces: a cost-benefit analysis. Vaccine 2000; 18(26): 3005-3010 Indexing Status Subject indexing assigned by NLM MeSH Cost-Benefit Analysis; Hepatitis A /prevention & Hepatitis A Antibodies; Hepatitis A Vaccines; Hepatitis Antibodies /immunology; Humans; Immunization, Passive; Male; Military Personnel; Vaccination; Vaccines, Inactivated /immunology; Viral Hepatitis Vaccines /immunology; control AccessionNumber 22000006391 Date bibliographic record published 31/07/2003 Date abstract record published 31/07/2003 |
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