A Collaborative Analysis of Data from Cohorts in Thailand, South Africa, Botswana, and the United Kingdom International Collaborative Study of Pediatric Diagnostic Tests JULY 19, 2011 Time to DNA-PCR Positivity in Non-Breastfed HIV-Infected Infants (Primarily Non-B HIV Subtype)

Background Accurate diagnostic tests to detect HIV infection in infants are critical to ensure early treatment HIV DNA-PCR has imperfect sensitivity in the first two weeks of life Previous studies found that time to HIV DNA-PCR positivity increase by about 15% with ZDV prophylaxis compared with no antiretrovirals (ARV) Impact of combination ARV prophylaxis is not well characterized; no single cohort can adequately address this question

Goals Combine data from several cohorts of non- breastfeeding HIV-infected mother-infant pairs  Initial phase: cohorts with primarily non-B HIV subtype Estimate the time to DNA-PCR positivity in non-breastfed HIV-infected infants Assess differences in time to DNA-PCR positivity according to maternal/infant ARV regimen

Inclusion/Exclusion Criteria Inclusion criteria:  Infant HIV-infected and has at least one DNA- PCR result before age 3 months  Maternal HIV diagnosis before or within 1 month after birth Excluded diagnostic tests with missing result or missing age at time of blood draw Excluded one infant whose mother’s ARV exposure was unknown

Statistical Methods Used methods for interval-censored data  Timing of HIV infection uncertain; in interval between last negative and first positive DNA-PCR test Estimated the cumulative probability of DNA-PCR positivity according to age and ARV  Non-parametric methods; Turnbull algorithm, Wilcoxon test Exploratory regression modeling to adjust for potential confounders  Parametric methods; assumed Weibull distributions with proportional hazards; likelihood ratio test

Participating Cohorts CohortCountryBirth Years Number of Infants (Tests) MASHIBotswana (91) Infant Diagnostic Study South Africa (83) NSHPC/HPAUK (African origin) (181) PHPTThailand (678) Thai/CDCThailand (370) Total 432 (1403)

Infants Grouped by Most Complex Maternal/Infant ARV Infant ARV Prophylaxis Maternal ARV during Trimester of Delivery No ARV Single NRTI sdNVP (+/- ZDV)>3 ARVs No ARV Single NRTI sdNVP (+/- ZDV) >3 ARVs No ARV = Mother and infant did not receive ARV at any time (n=125) Single NRTI = Mother or infant received single NRTI (n=159) sdNVP (+/- ZDV) = Mother or infant received sdNVP +/- ZDV (n=105) >3 ARVS = Mother or infant received >3 ARVs (n=43)

Demographics No ARV (n=125) Single NRTI (n=159) sdNVP +/- ZDV (n=105) >3 ARVs (n=43) Year of Birth Country Where HIV Acquired Botswana South Africa00272 Zimbabwe83210 Nigeria4106 Other African Country75021 Thailand

Characteristics ( median [25 th -75 th percentile]) No ARV (n=123) Single NRTI (n=159) sdNVP +/- ZDV (n=79) >3 ARVs (n=43) P value (Kruskal- Wallis) Maternal CD4 Near Delivery 410 [ ] 296 [ ] 284 [ ] 290 [ ] < Maternal Viral Load Near Delivery 67,590 [26, ,174] 14,125 [2,963 – 39,363] 41,496 [12,448 – 94,575] 6,000 [ ,666] < Gestational Age at Delivery 39 [35-43] 38 [33-43] 38 [33-43] 37 [30-45] < Delivery Type: Vaginal CS no labor/ROM CS with labor/ROM 92% 2% 6% 78% 9% 13% 80% 5% 15% 25% 40% 35% <

Cumulative Probability of Positive DNA-PCR by Age (Non-Parametric) P value (Wilcoxon) = ARV Group Number of infants Birth- 1 day <14 days < 30 days <42 days <90 days <370 days No ARV Single NRTI sdNVP +/- ZDV >3 ARVs

Cumulative Probability of Positive DNA-PCR by Age (Subset: 143 infants negative at birth or day 1) P value (Wilcoxon) = ARV Group Number of infants <14 days <30 days <42 days <90 days <370 days No ARV Single NRTI sdNVP+/- ZDV >3 ARVs

Cumulative Probability of Positive DNA-PCR by Age (Parametric - separate Weibull models, unadjusted)

Adjustment for Confounders: Infants who Received ARV (Parametric, Proportional Hazards; HR >1 Means Earlier Positivity) ARV GroupUnadjusted Hazard Ratio [95% CI] Adjusted Hazard Ratio [95% CI] Single NRTI1.44 [1.00 – 2.09]1.44 [ ] sdNVP+/- ZDV1.56 [1.06 – 2.30]1.39 [ ] >3 ARVs 1.0 P value for ARV Group * *P value for CD4 = 0.80, viral load =0.89, gestational age=0.44, delivery type =0.91

Summary and Conclusions Lower DNA-PCR positivity at birth and greater increase in positivity by 14 days of age in HIV- infected, non-breastfed infants who had no ARV vs. those who had maternal or infant ARV  Suggests ARV prevents a large proportion of intrapartum transmission Nonparametric estimates of the probability of DNA- PCR positivity by age differed significantly according to ARV group  Time to DNA-PCR positivity was later with receipt of >3 ARVs than with single NRTI or sd-NVP (+/- ZDV)

Summary and Conclusions (2) In preliminary parametric regression modeling, the association between ARV group and time to positivity did not remain statistically significant  However, adjustment did not change the hazard ratios and the confidence intervals were mostly above 1.0  The small number of infants exposed to > 3 ARVs limited the statistical power to detect a difference; further study is needed Our results may have implications for scheduling final HIV PCR diagnostic testing, particularly when resources are limited.

International Collaborative Study of Pediatric Diagnostic Tests – Collaborators R. Balasubramanian D.E. Shapiro M.G. Fowler K. Dominguez P. Tookey J. Masters J. Tosswill M. Lallemant N. Ngo-Giang Huang M. McConnell P. Mock G. Sherman S. Lockman V. Novitsky P. Palumbo S. Nesheim B. Bohannon K. Rich M. Hughes We gratefully acknowledge the study participants