Rapid HIV vs. ELISA screening in a low risk mexican american population presenting in labor: A cost-effectiveness analysis

POPULATION PRESENTING IN LABOR: A COST-EFFECTIVENESS ANALYSIS NORA DOYLE, JUDY LEVISON, MICHAEL GARDNER, University of Texas Health Science Center at Houston, Obstetrics, Gynecology, and Reproductive Sciences, Houston, Texas, Baylor College of Medicine, Obstetrics and Gynecology, Houston, Texas OBJECTIVE: Mother-to-child transmission (MTCT) of HIV is the most common cause of new pediatric HIV cases in the United States. CDC recommendations endorse rapid HIV testing to high risk women to quicken antiretroviral therapy. ELISA has been shown to have a high false positive rate in low risk Mexican American(MA) women. We sought to compare the cost effectiveness of Oraquick (OQ) vs. ELISA testing for a low risk population of MA women who present in labor. STUDY DESIGN: Using Decision analysis techniques we tested 3 strategies: (1) No testing; (2) Testing with ELISA/confirmed by Western blot (WB); (3) OQ/ confirmed by WB. All seropositive parturients received zidovudine (AZT) treatment (tx) in labor. Baseline assumptions: Incidence HIV in MA mothers = 0.5%, MTCT with no tx – 25%, with tx in labor – 10%, Sensitivity of ELISA = .98, Positive predictive value (PPV) of ELISA = .10, Sensitivity/ Specificity of OQ test = .99/1.00, PPV of OQ= .83-1.0, Sensitivity/Specificity of WB = .97/.99, Costs: ELISA=$5, OQ = $15, WB = $25, AZT tx = $76 for 12 hours labor, neonatal tx = $2.50, lifetime tx of HIV + child = $194,250. Sensitivity analyses were done over a wide range of assumptions, including costs of tests, sensitivity of OQ, PPV of ELISA/OQ, and costs of treatments. RESULTS: OQ was the preferred strategy at $98 spent per HIV negative child vs $243 with a no testing strategy and $499 for ELISA testing. Much of the cost of the ELISA strategy was due to the tx of women and infants with false positive tests. Sensitivity analysis over test costs, test sensitivity, and other variables found the analysis results to be robust. Threshold analysis revealed if the cost remained under $160.49, OQ was the dominant test. CONCLUSION: In a low prevalence population universal use of OQ is cost effective due to the low rate of false positives thus preventing the emotional and economic costs of unnecessary treatment for HIV to the new mother and her family. Further advantages of OQ include point of care testing with concomitant rapid results assisting the obstetrical provider in care of the patient. 179 METABOLIC ACTIVATION OF 2’, 3’-DIDEHYDRO-3’-DEOXYTHYMIDINE (D4T) IN ISOLATED MATERNAL AND FETAL PERIPHERAL BLOOD MONONUCLEAR CELLS AT TERM GESTATION ASHER BASHIRI, MOSHE MAZOR, IRIS OHEL, ARIE KOIFMAN, ESTHER MANOR, MAZAL RUBIN, RIAD AGBARIA, Soroka University Medical Center, Obstretric and Gynecology, Beer-Sheva, Israel, Soroka University Medical Center, Obstretric and Gynecology, Beer Sheva, Israel, Soroka University Medical Center, Obstetric and Gynecology, Beer-Sheva, Israel, Soroka University Medical Center, Obstetrics and Gynecology, Beer-Sheva, Israel, Soroka University Medical Center, Genetics Institute, Beer-Sheva, Israel, Ben-Gurion University of the Negev, Clinical Pharmacology, BeerSheva, Israel OBJECTIVE: Administration of anti-HIV drugs to HIV-infected pregnant women during the antepartum period and in labor can reduce the risk of mother-to-child HIV transmission. 20,30-Dideoxy-20,30-Didehydrothymidine (D4T, stavudine) is a potent antiviral agent for treating HIV-infections. D4T is phosphorylated in cytoplasm of a target cell to produce mono, di, and triphosphate metabolites. The d4T-triphosphate (D4TTP) exerts its antiviral activity by inhibition of HIV reverse transcriptase and termination of viral DNA synthesis. The aims of tudy were to examine the phosphorylation rate and incorporation of d4T into cellular DNA in maternal and fetal isolated peripheral mononuclear cells (PMNCs) at term gestation. STUDY DESIGN: Maternal PMNCs were isolated from blood drawn from HIV-seronegative pregnant women (n = 6, 36-40 weeks) prior to delivery. Immediately after delivery, cord blood was collected and fetal PMNCs were isolated. Fresh isolated maternal and fetal PMNCs were maintained in RPMI medium and incubated with [3H]-D4T, 10 mM, 5 mCi/ml, for 24 hrs. Cells were then collected and methanolic extracts were prepared for drug metabolites determination by HPLC. D4T incorporation into cellular DNA was determined by measuring radioactivity in cell pellets. RESULTS: The levels of the mono, and diphosphate of D4T were similar in maternal and fetal PMNCs, while D4TTP levels in fetal PMNCs were significantly higher compared with levels measured in maternal PMNCs, 0.050 G 0.008 and 0.035 G 0.011 pmoles/million cells, respectively. Furthermore, no significant difference was found in the levels of D4T incorporated into cellular DNA of maternal and fetal PMNCs, 0.026 G 0.009 and 0.038 G 0.027 pmoles/ million cells, respectively. CONCLUSION: Our results demonstrate that fetal PBMCs at term gestation are able to take up D4T and to efficiently generate its active metabolite-D4TTP, even at higher levels than the maternal PBMCs. These results have major importance in enabling better treatment to HIV-infected pregnant women and their fetuses.