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Acyclovir prophylaxis in late pregnancy to prevent neonatal herpes: a cost-effectiveness analysis |
Randolph A G, Hartshorn R M, Washington A E |
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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 Antiviral (Acyclovir) prophylaxis in the prevention of neonatal herpes.
Economic study type Cost-effectiveness analysis.
Study population A hypothetical cohort of 10,000 pregnant women with at least one previously documented outbreak of genital herpes.
Setting Hospital. The study was conducted in the USA.
Dates to which data relate The effectiveness data were partly derived from studies published in 1996. Whilst some of the resource use data were derived from information published in 1993 (additional costs from caesarean hospital charges relative to those associated with vaginal deliveries) and 1995 (drug acquisition costs), no dates were reported for the remainder of the data. The price year was not clearly stated.
Source of effectiveness data Effectiveness data were derived from a literature review and from opinion.
Modelling A decision tree was used to combine estimates of probability, consequence and costs of the four alternative options. The model included the costs associated with the procedures (therapies, modes of delivery and diagnostic tests) as well as the lifetime medical and nonmedical costs over the lifespan to age 65 for the entire cohort of children with cerebral palsy. The model used population-based data on relevant prevalence and incidence rates from the USA.
Outcomes assessed in the review The efficacy of acyclovir in preventing recurring lesions at delivery and in preventing asymptomatic viral shedding at delivery were the outcomes assessed in the review.
Study designs and other criteria for inclusion in the review Randomised controlled trials.
Sources searched to identify primary studies MEDLINE was 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 Two studies were included.
Methods of combining primary studies Investigation of differences between primary studies Results of the review The efficacy of acyclovir was estimated to be 0.80 (range: 0.45 -0.95), both for preventing lesions and for preventing asymptomatic shedding.
Methods used to derive estimates of effectiveness Estimates were derived from best guesses.
Estimates of effectiveness and key assumptions The efficacyof caesarean delivery in reducing transmission of HSV was 0.80 (range: 0 - 0.80).
The model used the following as additional epidemiological parameter values (estimates):
0.14for prevalence of maternal HSV lesion at delivery;
0.3for rate of asymptomatic shedding of HSV;
0.1for transmission rate from mother to baby;
0.227for caesarean section rate in the population;
and 0.80 and 1.00, respectively, for the sensitivity and specificity of HSV culture on neonates (this was based on data from one study published in 1989).
Measure of benefits used in the economic analysis The measures of benefits used in the economic analysis were cases of neonatal HSV prevented, and cases of neonatal death or disability averted. These benefits were estimated using a model.
Direct costs Some quantities of resource use were reported separately from the costs. The costs included were: acyclovir course per patient, caesarean (incremental over vaginal), screening of exposed infants, acute hospital care for neonatal herpes and incremental lifetime medical and developmental services. Costs were discounted at 5% per annum until the age of 65 years for the children concerned. The price year was not reported. The data were derived from hospital charge data and data from a cohort of herpes-infected neonates cared for at a University hospital in San Francisco, California (quantities of resource use were provided).
Sensitivity analysis The robustness of the model was tested by varying the effectiveness of acyclovir (0.95 and 0.45), HSV transmission rate (0.004) and no effectiveness of caesarean delivery for strategies A, B and C.
Estimated benefits used in the economic analysis In the model cohort (10,000 individuals), strategy B prevents a higher number of neonatal HSV cases (5.5), followed by C (5.0), A (2.8) and D (nil). The results in terms of cases of neonatal death or disability prevented were not reported separately.
Cost results The most costly strategy was A ($4,056,203), followed by B ($3,076,749), C ($2,363,634) and D ($361,724).
Synthesis of costs and benefits The (discounted) costs per case of neonatal HSV prevented (incremental over D) were: $1,319,457 (A), $493,641 (B), $400,382 (C). The costs per neonatal death or case of disability prevented were $3,012,459 (A), $1,127,034 (B) and $914,114 (C). Results are sensitive to assumptions of asymptomatic shedding (only mentioned in the text) and the 0.45 value for the efficacy of acyclovir. Note that the discount rate used in the above results was 5%, whilst the price year for these results was not clearly stated.
Authors' conclusions Oral acyclovir prophylaxis in late pregnancy for women with recurrent genital herpes is more cost-effective than the current strategy of caesarean delivery for all women presenting with genital herpes lesions.
CRD COMMENTARY - Selection of comparators These appear reasonable since they refer to commonly used options for preventing HSV transmission to neonates in women with recurrent HSV.
Validity of estimate of measure of benefit The comprehensiveness of the literature search and the rigour of the review are questionable and, therefore, cast doubt on the validity of the effectiveness study.
Validity of estimate of costs Indirect costs were omitted, as well as the year of valuation and the possible use of deflators. Additionally, unit costs and quantities of resource use were not reported separately in the study.
Other issues The implications of the uncertainty in the data for the study results were not thoroughly investigated in the sensitivity analysis, which is an important consideration in a study based on a model. The reader is not given visibility of the origin and quality of such evidence, which weakens the credibility of the model. Additionally, since resources were not presented separately from unit costs and it is unclear whether or not the costs estimates contain charge elements, the external validity of the study is open to question. Readers should also bear in mind that the difference in obstetric practice between the USA and the UK might also pose additional problems of generalisability.
Implications of the study Oral acyclovir prophylaxis in late pregnancy for women with recurrent genital herpes may be more cost-effective than a strategy of caesarean delivery for all women presenting with genital herpes lesions. However, a final word on this will have to await additional studies on the subject.
Source of funding Supported by grant Nos HS07373-01 and HS00106-01 from the Agency for Health Care Policy and Research and an award from the Student Research Committee, University of California, San Francisco, School of Medicine to R M Hartshorn.
Bibliographic details Randolph A G, Hartshorn R M, Washington A E. Acyclovir prophylaxis in late pregnancy to prevent neonatal herpes: a cost-effectiveness analysis. Obstetrics and Gynecology 1996; 88(4 Part 1): 603-610 Indexing Status Subject indexing assigned by NLM MeSH Acyclovir /administration & Administration, Oral; Adult; Antiviral Agents /administration & Cesarean Section; Cost-Benefit Analysis; Decision Support Techniques; Female; Health Care Costs; Herpes Genitalis /congenital /drug therapy /economics /prevention & Humans; Infant, Newborn; Infectious Disease Transmission, Vertical /prevention & Pregnancy; Pregnancy Complications, Infectious /drug therapy; Recurrence; control; control; dosage /economics; dosage /economics AccessionNumber 21996000931 Date bibliographic record published 28/02/1999 Date abstract record published 28/02/1999 |
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