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Session 24 Oral Abstracts
HIV Drug Resistance: Selection, Persistence, and Impact of Response
Thursday, 10 am - 12:30 pm
Presentation Time: 11:45 am
Auditorium


103
Effectiveness of Single-dose Nevirapine in a Second Pregnancy
Neil Martinson*1,2, L Pumla2, L Morris3, M Ntsala3, A Puren3, C Chezzi3, P Dhlamini2, S Cohen3, G Gray2, J Steyn2, and J McIntyre2
1Johns Hopkins Univ, Baltimore, MD, USA; 2Univ of the Witwatersrand, South Africa; and 3Natl Inst for Communicable Diseases, Johannesburg, South Africa

Background:  Single-dose Nevirapine (sdNVP) given to HIV-infected mothers and their newborns is effective in reducing mother-to-child transmission of HIV. With time, an increasing proportion of women will be exposed to sdNVP in subsequent pregnancies. A theoretical obstacle to the use of sdNVP in a second pregnancy is NVP resistance following initial exposure which may reduce efficacy of the drug when used again. The primary aim of this pilot study was to compare rates of mother-to-child transmission of HIV in women exposed to sdNVP in 2 successive pregnancies (cases) with a group of age, clinic, and enrollment-time matched multiparous controls exposed to sdNVP once. We report a preliminary unmatched analysis of this case cohort study.

Methods:  Participants were identified in 13 prenatal clinics of the Soweto program to prevent mother-to-child transmission. They were enrolled when pregnant, if evidence of provision of sdNVP in the previous pregnancy was available. Cases did not breastfeed their previous child. Two controls were selected for each case. Maternal viral load, CD4 count, and HIV resistance (ViroSeq Genotyping) were ascertained prior to sdNVP and at 6 weeks postpartum. Infection in infants was determined at 6 weeks by DNA-PCR.

Results:  Results of 177 mother infant pairs are available. The median time between deliveries in the cases was 22 months (IQR 15 to 27). The single woman with baseline resistance did not transmit HIV to her infant.

 

 

Cases

n=68 mothers

Controls

n=118 mothers

p value

Age at enrollment. (IQR)

28 (23–31)

28.5 (26­32)

0.06

Caesarian section

22.6%

20.0%

0.702

CD4 (IQR)

enrollment

410 (273–592)

350 (208­509)

0.113

Viral load

(IQR)

enrollment

13,400 (3980–54,400)

22,500 (6630–92,900)

0.121

6 weeks

22,650 (4390–72,000)

35,550 (6690–121,000)

0.551

Resistance

baseline

1/50 (2.0%)

0/93

0.751

6 weeks

13/34 (38.2%)

34/68 (50.0%)

0.261

HIV PCR      6 weeks

9/66 (13.7%)

5/119 (4.2%)

0.042

 

Conclusions:  Preliminary data from this pilot study suggest that HIV-transmission in women receiving sdNVP a second time is higher than multiparous controls. However, the rates in cases are similar to other studies in the same population who have been exposed to sdNVP only once. Controls appear to have more advanced HIV which could explain higher resistance levels. Numbers of women attending PMTCT programs for a second or third time are increasing and data is urgently needed to better inform decision-making.

Keywords: nevirapine; mother to child transmission; resistance