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Background:  The performance of the rapid HIV antibody test, Determine ® HIV-1/2, has been evaluated in different settings with higher sensitivity and specificity than EIA and Western blot. However, the test has been evaluated mainly on male adults with a paucity of data in pregnant women. In this study, we evaluated the sensitivity and specificity of the rapid test Determine HIV-1/2 in pregnant women at Tijuana General Hospital. In addition, we determined the timing of antiretroviral intervention at delivery.

Methods:  Pregnant women with unknown HIV status seeking prenatal care or who were admitted in labor and consented to participate in the study, had blood drawn for a rapid HIV test (Determine HIV-1/2). A confirmatory EIA and Western blot was performed. Sensitivity, specificity, and positive and negative predictive values were determined. In addition, time from blood collection to diagnosis and antiretroviral administration was recorded.

Results:  From March to November 2003, 1529 women who sought prenatal care and 1068 women in labor, received counseling and testing. HIV seroprevalence was significantly higher among women screened during labor (12 of 1068, 1.12%) than those seeking prenatal care (5 of 1529, 0.33%). There were 3 false positives in labor and 2 false positives during prenatal care, giving a sensitivity of 100%, specificity of 99.7%, positive predictive value of 80%, and negative predictive value of 100% for the women in labor. For the prenatal care group, the sensitivity was 100%, specificity 99.9%, positive predictive value 71%, and a negative predictive value of 100%. The mean time between blood collection and rapid test results was 80 minutes (range 20 to 205 minutes). Mean time between rapid test results and intravenous zidovudine (AZT) administration (6 patients) was 96 minutes (10 to 175 minutes). Mean time between the start of intravenous AZT and birth was 168 minutes (50 to 300 minutes). The mean time between blood collection and EIA results was 33 hours (6 to 120 hours). Eleven infants received oral AZT and the mean time between birth and oral AZT administration was 7 hours (2 to 16 hours). 

Conclusions:  These findings indicate that the rapid test Determine HIV-1/2 has a high sensitivity and specificity when used during prenatal care and in labor and delivery. Rapid HIV testing greatly diminishes the time to diagnosis and enables prompt intervention with ART in labor and delivery.

Keywords: Rapid HIV Testing; Pregnancy; Mexico