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The cost effectiveness of voluntary prenatal and routine newborn HIV screening in the United States |
Zaric G S, Bayoumi A M, Brandeau M L, Owens D K |
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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 Voluntary prenatal and routine newborn HIV screening in the USA.
Economic study type Cost-effectiveness analysis.
Study population The study population consisted of pregnant women and newborns in the USA. The perspective adopted was that of society.
Setting The study setting was hospital. The economic study was carried out in the USA.
Dates to which data relate Effectiveness and resource use data were collected from studies published between 1989 and 1999. Cost data were taken from studies published between 1993 and 1998. The price year was 1997.
Source of effectiveness data Effectiveness data were derived from a literature review and from expert opinion.
Modelling A decision analytic model was used to determine the cost-effectiveness of the three hypothetical HIV screening strategies.
Outcomes assessed in the review The review assessed the health benefits of early identification, enhanced prenatal screening, and routine newborn screening, vertical transmission rates, adherence, prenatal care behaviour, and test characteristics.
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 Summary statistics from individual studies were used.
Number of primary studies included At least 34 primary studies were included in the review.
Methods of combining primary studies Primary studies were combined using the narrative method.
Investigation of differences between primary studies Results of the review Full details of input variables for the model are reported in the paper. The following is a summary of the key values used.
Two thirds of HIV-infected pregnant women were tested. 95% of HIV-uninfected mothers and 80% of HIV-infected mothers seek prenatal care. 65% of all women who sought prenatal care accepted HIV screening, irrespective of HIV status. Current prenatal screening programmes identified 52% of HIV-infected women who were unaware of their infection. 84% of women knew their status before childbirth. 90% of HIV-infected women adhered to antiretroviral therapy. The breastfeeding rate was 30% among HIV-infected women who were not aware of their serostatus, and 2% among HIV-infected women who were aware of their serostatus. With enhanced prenatal screening, the proportion of HIV-infected women seeking prenatal care who consented to HIV screening was 95%. Antiretroviral therapy initiated after birth achieved 84.4% of the benefit achieved had it been initiated prenatally.
The vertical transmission rate with new antiretroviral therapy was 3%. Breastfeeding resulted in a relative risk of HIV transmission of 1.66. Vertical transmission probabilities for mothers who did not breastfeed were 3% if antiretroviral therapy was initiated during pregnancy, 26.6% if neither mother nor infant received antiretroviral therapy, and 6.7% for abbreviated routines in which only the infant received antiretroviral therapy, and it was initiated postnatally. Vertical transmission probabilities for mothers who did breastfeed were 5%, 44.2%, and 11.1%, corresponding to antiretroviral therapy initiated during pregnancy, no therapy, and therapy initiated after birth, respectively.
In terms of test characteristics: initial enzyme immunoassay (EIA) true-positive rate (TPR) accuracy was 0.995, initial EIA true-negative rate (TNR) accuracy was 0.994, confirmatory test bundle TPR accuracy was 0.99994, initial polymerase chain reaction (PCR) TPR accuracy was 0.932, initial PCR TNR accuracy was 0.932, confirmatory PCR TPR accuracy was 0.982, and confirmatory PCR TNR accuracy was 0.982.
Methods used to derive estimates of effectiveness Estimates of effectiveness were also derived from authors' assumptions.
Estimates of effectiveness and key assumptions Adherence rates with antiretroviral therapy for infants for the first 6 weeks after birth were 100%. Increased life expectancy for newborns and mothers was assumed to be 0 years (range: 0-4).
Measure of benefits used in the economic analysis The number of life years gained was used as the measure of benefits.
Direct costs Direct costs were discounted at an annual rate of 3%. Quantities and costs were reported separately. Direct costs included costs of screening, counselling, and treatment associated with the programmes, as well as savings in future health care costs for averted infant HIV infections. 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 obtained from the literature. The price year was 1997.
Statistical analysis of costs No statistical analysis was reported.
Indirect Costs Indirect costs were not included.
Sensitivity analysis One-way and two-way sensitivity analyses were conducted on key model parameters.
Estimated benefits used in the economic analysis The enhanced prenatal screening programme caused an additional 1.1 million women to be screened, identified 527 HIV-infected women, averted 150 newborn infections annually relative to current programmes, and resulted in 3,311 life years gained.
The newborn screening programme caused 3.9 million women to be screened, identified 1,061 HIV-infected women, averted 266 newborn infections annually relative to current programmes, and resulted in 5,878 life years gained.
Newborn screening when enhanced prenatal screening is already in place averted an additional 135 infections per year and resulted in 2,975 life years gained.
Cost results Total costs amounted to $29.4 million with enhanced prenatal screening and $40.9 million with newborn screening.
Synthesis of costs and benefits Enhanced prenatal screening cost $8,900 per life year gained or $195,700 per case of HIV averted.
Newborn screening cost $7,000 per life year gained or $153,600 per case of HIV averted.
Newborn screening, when enhanced prenatal screening was already in place, cost $10,600 per life year gained.
The sensitivity analyses revealed that the screening programmes are likely to be cost-effective over a wide range of assumptions.
Authors' conclusions Improved voluntary prenatal HIV screening of women and routine screening of newborns are cost-effective. Routine newborn screening becomes less attractive as the rate of voluntary prenatal screening increases. Improved participation in voluntary prenatal screening has the added benefit that mothers maintain their right to determine whether they are tested for HIV.
CRD COMMENTARY - Selection of comparators A justification was given for the comparator used, namely that it was a currently employed strategy. You, as a user of the database, should decide if these health technologies are relevant to your setting.
Validity of estimate of measure of effectiveness The authors undertook a comprehensive literature review to derive estimates for the model which seemed appropriate, although they 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 pooling primary effectiveness estimates could have been reported. The validity of the results was enhanced by appropriate and extensive sensitivity analyses to account for variability in the estimates.
Validity of estimate of measure of benefit The estimation of benefits was obtained directly from the effectiveness analysis through the modelling undertaken.
Validity of estimate of costs Good features of the cost analysis were that all relevant direct cost categories were included, quantities and costs were reported separately, the price year was reported, and direct costs were discounted. The validity of the cost results was also enhanced by appropriate sensitivity analyses over plausible ranges.
Other issues This was a very thorough paper which extensively reported its methods and results. The authors did make 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 considered pregnant women and newborns in the USA and this was reflected in the authors' conclusions. The authors stated that they did not consider the health benefit of reduced HIV transmission from HIV-infected women to people other than their newborns, which would make the programmes more cost-effective. They did not consider the impact of Caesarean section and other clinical and biological factors on vertical transmission rates. In terms of generalisability, the authors did not compare alternative strategies such as targeted newborn screening for women who refuse newborn screening.
Implications of the study The findings of the study suggest that both newborn routine screening and enhanced prenatal screening are cost-effective.
Source of funding M L Brandeau, A M Bayoumi and G S Zaric were supported by the Societal Institute of the Mathematical Sciences through a grant from the National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland USA. (R-01-09531). D K Owens was supported by a Career Development Award from the Veterans Affairs Health Services Research and Development Service, Washington DC, USA.
Bibliographic details Zaric G S, Bayoumi A M, Brandeau M L, Owens D K. The cost effectiveness of voluntary prenatal and routine newborn HIV screening in the United States. Journal of Acquired Immune Deficiency Syndromes 2000; 25(5): 403-416 Indexing Status Subject indexing assigned by NLM MeSH AIDS Serodiagnosis /economics /utilization; Cost-Benefit Analysis; Decision Support Techniques; Female; HIV Infections /diagnosis /prevention & Humans; Infant, Newborn; Infectious Disease Transmission, Vertical /prevention & Mass Screening /economics /utilization; Pregnancy; Pregnancy Complications, Infectious /diagnosis; Prenatal Diagnosis /economics /utilization; United States; control; control /transmission AccessionNumber 22001000145 Date bibliographic record published 30/09/2001 Date abstract record published 30/09/2001 |
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