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Hepatitis B immunization in a low-incidence province of Canada: comparing alternative strategies |
Wiebe T, Fergusson P, Horne D, Shanahan M, MacDonald A, Heise L, Roos L L. |
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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 A universal programme for Hepatitis B immunisation of children.
Type of intervention Screening and primary prevention.
Economic study type Cost-effectiveness analysis.
Study population Three hypothetical cohorts of infants, 10 year olds, and 12 year olds.
Setting Hospital. The economic study was set in Manitoba, Canada.
Dates to which data relate Effectiveness data were collected from studies published between 1971 and 1995. Resource use data were taken from a study published in 1993. Cost data were based on data collected from a teaching hospital in Winnipeg. The price year was 1993.
Source of effectiveness data Effectiveness information was derived from a literature review.
Modelling A lifetime Markov decision analytic model was used to determine the cost-effectiveness of the immunisation strategies in a low-incidence province in Canada.
Outcomes assessed in the review The review assessed compliance, prevalence, sensitivity and specificity of screening, immunity, effectiveness of interferon therapy, and the probability of cirrhosis and hepatocellular carcinoma.
Study designs and other criteria for inclusion in the review Effectiveness estimates were taken from studies typically with small sample sizes and short follow-up times. No further details were given.
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 Summary statistics from individual studies were extracted. No further details were given.
Number of primary studies included At least 22 primary studies were included.
Methods of combining primary studies Studies provided separate inputs for the model.
Investigation of differences between primary studies Results of the review Maternal screening compliance was 90%. The prevalence of maternal HBSAg+ was 0.61. The sensitivity and specificity of surface antigen screening was 97.50% and 98%, respectively. Compliance with universal immunisation was 90%. Compliance with immunisation in children of HBSAg+ mothers was 90%. The probability of hospitalisation following hepatitis in the perinatal period was 2.5%. The probability of death following hospitalisation with hepatitis in the perinatal period was 20%. The probability of natural immunity following acute hepatitis in the perinatal period was 4.5%. The probability of perinatal infection becoming long-term was 95%. Those with acute hepatitis progressed to natural immunity (0.95 - 0.05), HBSAg+/HBEAg+ (0.95 - 0.05), or death (0.0 - 0.0007/year above baseline). The loss of vaccine-induced immunity began at 2% and reached a maximum of 8% per year. Interferon therapy was provided to 34% of individuals with HBSAg+/HbeAg+ infection. The response rate to interferon was 32%. Those not responding to interferon therapy progressed to hepatocellular carcinoma (0.002 - 0.021/year) or cirrhosis (0.024/year). The probability of death after hepatocellular carcinoma was 0.95/year.
Measure of benefits used in the economic analysis The number of years of life saved was used as the measure of benefits. Benefits were discounted at an annual rate of 5%.
Direct costs Direct costs were discounted at an annual rate of 5%. Quantities and costs were reported separately. Direct costs included the costs of vaccine, office overheads, and travel time for public health nurses, physician billing for office visits, and hospital costs. The quantity/cost boundary adopted was that of the health service. The estimation of quantities and costs was based on actual data. Costs and quantities were collected from teaching hospitals in Winnipeg. The price year was 1993.
Indirect Costs Indirect costs were not included.
Sensitivity analysis Sensitivity analyses were performed on all model parameters.
Estimated benefits used in the economic analysis Cost results Cost results were not reported.
Synthesis of costs and benefits The incremental cost-effectiveness ratio of universal immunisation was Can$15,900 for infants, Can$97,600 for 10 year olds, and Can$184,800 for 12 year olds. Changes in the values of discount rates, immunisation costs, incidence rates of acute hepatitis, and the rate at which vaccine protection was lost substantially affected cost-effectiveness ratios.
Authors' conclusions A universal programme of HBV immunisation for infants appears to be economically practical in regions where HBV infection rates are low and stable.
CRD COMMENTARY - Selection of comparators A justification was given for the comparators used, namely currently employed strategy. You, as a user of this database, should decide if these health technologies are relevant to your setting.
Validity of estimate of measure of benefit The authors did not state that a systematic review of the literature had been undertaken. More information about the design of the review and the method of combining primary effectiveness estimates could have been reported. The estimation of benefits was obtained directly from the effectiveness analysis.
Validity of estimate of costs Some good features of the cost analysis were that all relevant cost categories were included, sensitivity analyses were conducted on costs and quantities, quantities and costs were reported separately, the price year was reported, and detailed information was provided on the methods of cost estimation for each cost category. It was unclear, however, whether charges were used to proxy prices.
Other issues The authors did not present their results selectively. The study considered infants, 10 year olds, and 12 year olds and this was reflected in the authors' conclusions. The authors made appropriate comparisons of their findings with those from other studies and the issue of generalisability to other settings was extensively addressed. Using a single incidence rate and compliance rate across age limits and regions limits the generalisability of the results. The results rest on the assumption that safe and effective infant HBV immunisation occurs when the vaccine is given concurrently with other routine vaccinations. The authors did not consider indirect costs and effects, such as increased productivity and less pain and suffering, but they pointed out that a broader societal viewpoint would more favourably support the cost-effectiveness of universal immunisation.
Implications of the study According to the authors, an universal infant immunisation programme seems justified from both the health and economic points of view. However, other factors need to be considered, including the availability of a safe and effective vaccine, national trends, the effect of multiple antigens, age-dependent rates of infection, and the impact of the disease from a broader, societal perspective.
Source of funding Supported by the Manitoba Centre for Health Policy and Evaluation by HEALNET (Health Evidence Application and Linkage Network), by the St Boniface General Hospital Research Centre, and by a National Health Research and Development Program Health Scientist Award to L Roos.
Bibliographic details Wiebe T, Fergusson P, Horne D, Shanahan M, MacDonald A, Heise L, Roos L L.. Hepatitis B immunization in a low-incidence province of Canada: comparing alternative strategies. Medical Decision Making 1997; 17(4): 472-482 Indexing Status Subject indexing assigned by NLM MeSH Carcinoma, Hepatocellular /mortality; Child; Cost-Benefit Analysis; Decision Support Techniques; Decision Trees; Female; Hepatitis B /complications /drug therapy /immunology /mortality /prevention & Humans; Immunization Programs /economics; Infant; Infant, Newborn; Interferons /economics /therapeutic use; Liver Cirrhosis /mortality; Manitoba /epidemiology; Markov Chains; Pregnancy; Prenatal Diagnosis /economics; control AccessionNumber 21997008356 Date bibliographic record published 31/05/2001 Date abstract record published 31/05/2001 |
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