Sarah White’s research while affiliated with University of Texas Southwestern Medical Center and other places

Background: False positive HIV screening tests in pregnancy may lead to unnecessary interventions in labor. In 2014, the Centers for Disease Control and Prevention released a new algorithm for HIV diagnosis using a 4th generation screening test, which detects antibodies to HIV as well as p24 antigen and has a shorter window period compared with prior generations. A reactive screen requires a differentiation assay, and supplemental qualitative RNA testing is necessary for nonreactive differentiation assay. One screening test, the ARCHITECT Ag/Ab Combo assay, is described to have 100% sensitivity and >99% specificity in non-pregnant populations; however, its clinical performance in pregnancy has not been well described. Objective: To determine the performance of the ARCHITECT assay among pregnant women at a large county hospital and to assess if the relative signal-to-cutoff ratio can be used to differentiate between false positive versus confirmed HIV infections in women with nonreactive differentiation assay. Study design: This is a retrospective review of 4th generation HIV testing in pregnant women at Parkland Hospital between June 1, 2015 and January 31, 2017. We identified gravidas screened using the ARCHITECT Ag/Ab Combo assay (index test), with reflex to differentiation assay. Women with reactive ARCHITECT and nonreactive differentiation assay were evaluated with a qualitative RNA assay (reference standard). We calculated sensitivity, specificity, predictive value, and false positive rate of the ARCHITECT screening assay in our population, and described characteristics of women with false positive HIV testing versus confirmed infection. Among women with nonreactive differentiation assay, we compared interventions among women with and without qualitative RNA assay result available at delivery, and examined relative signal-to-cutoff ratios of the ARCHITECT assay in women with false positive versus confirmed HIV infection. Results: A total of 21,163 pregnant women were screened using the ARCHITECT assay, and 190 tested positive. Of these, 33/190 (17%) women had false positive HIV screening tests (28 deliveries available for analysis), and 157/190 (83%) had confirmed HIV-1 infection (140 available for analysis). Diagnostic accuracy of the ARCHITECT HIV Ag/Ab Combo assay in our prenatal population (with 95%CI) was as follows: sensitivity 100%(97.7%-100%), specificity 99.8%(99.8%-99.9%), positive likelihood ratio 636(453-895), negative likelihood ratio 0.0(NA), positive predictive value 83%(77%-88%), and false positive rate 0.16%(0.11%-0.22%), with prevalence 7/1,000. Women with false positive HIV testing were younger and more likely of Hispanic ethnicity. Qualitative RNA assay (reference standard) was performed prenatally in 24(86%) and quantitative viral load in 22(92%). Interventions occurred more frequently in women without qualitative RNA assay result available at delivery, including intrapartum zidovudine (75% vs 4%, p=0.002), breastfeeding delay (75% vs 8%, p=0.001) and neonatal zidovudine initiation (75% vs 4%, p=0.002). ARCHITECT signal-to-cutoff ratio was significantly lower for women with false positive HIV tests compared to those with established HIV infection (1.89 [1.27, 2.73] vs 533.65 [391.12, 737.22], respectively, p<0.001). Conclusion: While the performance of the 4th generation ARCHITECT HIV Ag/Ab Combo assay among pregnant women is comparable to that reported in non-pregnant populations, clinical implications of using a screening test with positive predictive value of 83% in pregnancy are significant. When qualitative RNA assay result is unavailable, absence of risk factors in combination with ARCHITECT HIV Ag/Ab assay S/Co ratio <5 and nonreactive differentiation assay provide sufficient evidence to support deferral of unnecessary intrapartum interventions while awaiting qualitative RNA results.

INTRODUCTION Hyperemesis gravidarum is one of the most common indications for admission in pregnancy. Because some women require re-hospitalization, we hypothesized that the risk for readmission could be identified. The aim of this study was to use patient characteristics and index admission features to determine the risk for readmission. METHODS This was a retrospective cohort study of women admitted with hyperemesis gravidarum at our hospital. Hyperemesis gravidarum was defined as intractable nausea and vomiting with either electrolyte derangement, >10 lb weight loss, or persistent ketonuria suggesting dehydration. Women with alternative etiologies for persistent nausea and vomiting were excluded. Women requiring more than one hospitalization for hyperemesis gravidarum were compared to those with one admission to determine if any factors were associated with readmission during the same pregnancy. RESULTS Between 2009 and 2014, a total of 144 women were admitted with hyperemesis gravidarum that comprised 247 hospital admissions. Fifty-one (35%) women required more than one hospitalization for hyperemesis gravidarum. Factors examined included maternal age, race, parity, habitus, substance use, smoking, and psychiatric illness. None of these features including length of initial hospitalization were found to be associated with the need for readmission. Of those delivered at our hospital, readmission was not associated with differing perinatal outcomes. CONCLUSION More than one-third of women with hyperemesis gravidarum required readmission at our hospital. Factors associated with need for readmission did not include maternal demographic features, substance use, or psychiatric illness. The length of hospitalization for the initial admission also was not associated with later readmission.