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Field evaluation of a combination of monospecific enzyme-linked immunosorbent assays for type-specific diagnosis of human immunodeficiency virus type 1 (HIV-1) and HIV-2 infections in HIV-seropositive persons in Abidjan, Ivory Coast |
Nkengasong J N, Maurice C, Koblavi S, Kalou M, Bile C, Yavo D, Boateng E, Wiktor S Z, Greenberg 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 Combination of monospecific enzyme-linked immunosorbent assays (ELISAs) (CME) for type-specific diagnosis of human immunodeficiency virus type 1 (HIV-1) and HIV-2 infection.
Economic study type Cost-effectiveness analysis.
Study population Populations in West Africa, including tuberculosis patients, blood donors, hospitalised patients, persons who voluntarily sought HIV testing, pregnant women and female sex workers.
Setting Hospital. The study was carried out in Abidjan, Ivory Coast, West Africa.
Dates to which data relate The main effectiveness data were obtained from a single trial conducted in 1996. Resource and cost data were mainly derived from 1996 sources. The price year was not stated.
Source of effectiveness data The estimates of the results of Peptilav, LIA (synthetic-peptide-based line immunoassays) and CME serodiagnosis were obtained from a single trial.
Link between effectiveness and cost data The costing was undertaken prospectively on the same patient sample as that used in the effectiveness study.
Study sample Overall, a panel of 1,608 sera was included in the analysis and evaluated retrospectively and a panel of 821 sera was included in the analysis and evaluated prospectively. Power calculations to determine the sample size were not given.
Study design Case series. The duration of follow-up was not stated but is not relevant in this situation. There was no loss to follow-up.
Analysis of effectiveness The analysis of the effectiveness was based on the whole sample. The primary health outcomes were the results of Peptilav, LIA and CME serodiagnosis.
Effectiveness results In the retrospective evaluation, overall, 1,535 (95.5%) of 1,608 sera gave concordant results in the CME and Peptilav tests; 73 sera (4.5%) yielded discordant results, one of which was a confirmed HIV antibody-negative specimen that was reactive in CME. Of the 428 sera that were HIV-1 antibody positive by Peptilav, 100% were scored as HIV-1 antibody positive by CME. All 361 Peptilav-confirmed HIV-2 antibody-positive sera were strongly positive by the ICE-HIV-2 assay. However, 12.5% of these sera were classified HIV-D (weakly reactive to both the Peptilav HIV-1 and HIV-2 bands). Of the 371 sera classified as HIV-D by Peptilav, 92.7% were confirmed HIV-D by CME, 5.7% were classified HIV-1 and 1.6% were classified as HIV-2. Additional testing of the discrepant samples by two HIV differentiation assays gave results that agreed with those by CME for most of the sera. In the prospective evaluation, of the 821 consecutive sera tested, 267 (32.5%) were reactive in the HIV-1 -HIV-2 mixed-antigen ELISAs and were tested by both Peptilav and CME. Overall, 215 (80.5%) of 267 sera gave concordant results in the CME and Peptilav tests; 52 sera (19.5%) yielded discordant results, one of which was a confirmed HIV antibody-negative specimen that was reactive in CME. Of the 106 sera that were HIV-1 antibody positive by Peptilav, 100% were scored as HIV-1 antibody positive by CME. All 41 Peptilav-confirmed HIV-2 antibody-positive sera were strongly positive by the ICE-HIV-2 assay. However, one of these sera was classified HIV-D (weakly reactive to both the Peptilav HIV-1 and HIV-2 bands). Of the 120 sera classified as HIV-D by Peptilav, 57.5% were confirmed HIV-D by CME, 39.2% were classified HIV-1 and four were classified as HIV-2. All 47 samples scored as HIV-1 by CME and 2 of 4 HIV-2 sera gave concordant results by INNO-LIA.
Clinical conclusions A testing strategy comprising two monospecific ELISAs can serotype HIV-1 and HIV-2 infections in HIV-seropositive persons more accurately than a strategy based on an LIA assay. In both the retrospective and the prospective evaluation, the overall concordance between CME and Peptilav testing was high and when these two strategies gave discordant results, the results of the supplemental testing agreed with the results of the CME strategy.
Measure of benefits used in the economic analysis No summary benefit measure was used in the analysis and as such the benefits were considered to be the same as the outcome measures.
Direct costs The cost of screening was included in the analysis. Resource and cost data were reported separately. Discounting was not undertaken due to the short study period. The quantity/cost boundary adopted was the hospital. The price year was not stated.
Statistical analysis of costs Sensitivity analysis No sensitivity analysis was performed.
Estimated benefits used in the economic analysis In the retrospective evaluation, overall, 1,535 (95.5%) of 1,608 sera gave concordant results in the CME and Peptilav tests; 73 sera (4.5%) yielded discordant results, one of which was a confirmed HIV antibody-negative specimen that was reactive in CME. Of the 428 sera that were HIV-1 antibody positive by Peptilav, 100% were scored as HIV-1 antibody positive by CME. All 361 Peptilav-confirmed HIV-2 antibody-positive sera were strongly positive by the ICE-HIV-2 assay. However, 12.5% of these sera were classified HIV-D (weakly reactive to both the Peptilav HIV-1 and HIV-2 bands). Of the 371 sera classified as HIV-D by Peptilav, 92.7% were confirmed HIV-D by CME, 5.7% were classified HIV-1 and 1.6% were classified as HIV-2. Additional testing of the discrepant samples by two HIV differentiation assays gave results that agreed with those by CME for most of the sera. In the prospective evaluation, of the 821 consecutive sera tested, 267 (32.5%) were reactive in the HIV-1 -HIV-2 mixed-antigen ELISAs and were tested by both Peptilav and CME. Overall, 215 (80.5%) of 267 sera gave concordant results in the CME and Peptilav tests; 52 sera (19.5%) yielded discordant results, one of which was a confirmed HIV antibody-negative specimen that was reactive in CME. Of the 106 sera that were HIV-1 antibody positive by Peptilav, 100% were scored as HIV-1 antibody positive by CME. All 41 Peptilav-confirmed HIV-2 antibody-positive sera were strongly positive by the ICE-HIV-2 assay. However, one of these sera was classified HIV-D (weakly reactive to both the Peptilav HIV-1 and HIV-2 bands). Of the 120 sera classified as HIV-D by Peptilav, 57.5% were confirmed HIV-D by CME, 39.2% were classified HIV-1 and four were classified as HIV-2. All 47 samples scored as HIV-1 by CME and 2 of 4 HIV-2 sera gave concordant results by INNO-LIA.
Cost results The cost of screening sera simultaneously by two HIV-1 HIV-2 combined ELISAs was $1,970. The cost of screening sera by HIV antibody-positive was $908 for the CME strategy and $5,073 by the Peptilav-combined ELISAs and the type-specific strategies. A cost saving in favour of the CME strategy (59%) was realised.
Synthesis of costs and benefits Costs and benefits were not combined.
Authors' conclusions A combination of highly sensitive and specific commercially available monospecific ELISAs is a reliable and cost-effective strategy for type-specific serodiagnosis of HIV-1 and HIV-2 infections in HIV-seropositive persons and therefore represents a recommended strategy in areas where both HIV-1 and HIV-2 are endemic.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator is clear. The classic strategy for the serodiagnosis of HIV infection includes Peptilav and LIA. You, as a user of this database, should consider whether these are widely used health technologies in your own setting. Validity of estimate of measure of benefit No summary benefit measure was included and as such the authors conducted a cost and outcomes analysis. The data do not seem to have been used selectively. Validity of estimate of costs Resource quantities were reported separately from the prices. Adequate details of methods of quantity/cost estimation were given. Important cost items do not appear to have been omitted. However, only a prospective cost analysis was conducted. Other issues The authors' conclusions are likely to be justified given the uncertainties in the data. The issue of generalisability was not addressed. However, appropriate comparisons were made with other studies supporting the clinical results from the present investigation and results do not appear to have been presented selectively. Implications of the study Further analysis is required which uses different cut-off values to discriminate between infections. Source of funding Supported by the Division of HIV/AIDS Prevention, National Center for HIV, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Ga.
Bibliographic details Nkengasong J N, Maurice C, Koblavi S, Kalou M, Bile C, Yavo D, Boateng E, Wiktor S Z, Greenberg A E. Field evaluation of a combination of monospecific enzyme-linked immunosorbent assays for type-specific diagnosis of human immunodeficiency virus type 1 (HIV-1) and HIV-2 infections in HIV-seropositive persons in Abidjan, Ivory Coast. Journal of Clinical Microbiology 1998; 36(1): 123-127 Indexing Status Subject indexing assigned by NLM MeSH Acquired Immunodeficiency Syndrome /diagnosis; Cost-Benefit Analysis; Enzyme-Linked Immunosorbent Assay; HIV Seropositivity /diagnosis; HIV-1; HIV-2; Humans; Prospective Studies; Retrospective Studies; Serologic Tests /economics AccessionNumber 21998000097 Date bibliographic record published 31/07/1999 Date abstract record published 31/07/1999 |
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