99
Mother-to-Child HIV Transmission Risk According to Antiretroviral Therapy, Mode of Delivery, and Viral Load in 2895 U.S. Women (PACTG 367)
D Shapiro*1, R Tuomala2,3, H Pollack4, S Burchett3,5, J Read6, M Cababasay1, J McNamara7, and G Ciupak8
1Harvard Sch. of Publ. Hlth., Boston, MA, USA; 2Brigham and Women's Hosp., Boston, MA, USA; 3Harvard Med. Sch., Boston, MA, USA; 4New York Univ. Sch. of Med., NY, USA; 5Children's Hosp.; 6NICHD, NIH, DHHS, Bethesda, MD, USA; 7NIAID, NIH, DHHS, Bethesda, MD, USA; and 8Frontier Sci. and Technology Res. Fndn., Buffalo, NY, USA
Background: Antiretroviral therapy (ART) during pregnancy and cesarean section before
labor and membrane rupture (ECS) each reduce vertical HIV transmission, but
their effects among women with low viral load are not well characterized.
Methods: Abstraction of medical records
of HIV-infected pregnant women at 67 U.S. clinical sites (PACTG 367).
Data on pregnancies resulting in singleton live birth(s) between January 1, 1998 and December 31, 2001 with
known infant HIV status were analyzed using c2, Fisher Exact, and trend tests, as well as
logistic regression analyses.
Results: Of 2895 singleton births with
known HIV infection status, 85 infants were HIV-infected (overall transmission
rate: 2.9%; 95% CI 2.4 - 3.6%). From
1998 to 2001, overall transmission rate decreased (4.2% to 2.2%, p = 0.002), along with increases in
multi-agent (>2 antiretrovirals) ART
use (75% to 90%, p <0.001) and ECS
(12% to 33%, p <0.001). Transmission
rate increased with higher plasma HIV RNA at last antenatal measurement
(<1000: 0.7%; 1000 to 9999: 2.1%; >10,000: 5.9%; p <0.001). Transmission rate was
lower with multi-agent than with single-agent ART
(1.4% vs 5.1%, p <0.001) and did
not differ significantly according to classification of agents used. Transmission
rate with ECS did not differ significantly from that for vaginal delivery (2.2%
vs. 3.5%). Transmission rate and univariate OR (95% CI) according to last
antenatal HIV RNA were:
Last Antenatal HIV RNA, Copies/mL [n]
|
Risk Factor
|
<103 [1736]
|
103-104 [567]
|
≥104 [372]
|
No RNA in chart
[220]
|
|
Multi-agent vs Single ART
|
0.6% vs. 2.2%
0.3 (0.1-1.1)
|
1.9 vs. 2.7%
0.7 (0.2-3.2)
|
4.2 vs. 11.5%
0.3 (0.1-0.9)*
|
5.1 vs. 11.9%
0.4 (0.1-1.6)
|
|
ECS vs Vaginal Deliv.
|
0.8% vs. 0.7%
1.2 (0.2-4.3)
|
2.8 vs. 1.9%
1.5 (0.4-5.0)
|
4.1 vs. 7.3%
0.5 (0.2-1.5)
|
8.3 vs. 22.4%
0.3 (0.1-0.9)*
|
* = p <0.05
In a preliminary multivariate analysis of the subgroup of women with last
RNA<1000, after controlling for RNA <400 vs >400, last CD4+
cell count, duration of membrane rupture, and preterm birth, overall transmission rate differed significantly with multi- versus single-agent ART (adjusted OR 0.2, 95% CI 0.04 - 0.8) but not
with ECS versus vaginal delivery (adjusted OR 0.7, 95% CI 0.03 - 4.6). Results
were similar after excluding presumed in utero transmissions (infant HIV+
<72 hours after birth).
Conclusions: Over time, multi-agent ART and ECS increased and transmission rate
decreased. After controlling for other risk factors, transmission rate among
women with plasma HIV RNA<1000 did not differ significantly according to
delivery route but was significantly lower with multi- versus single-agent ART.
Keywords: prevention of perinatal HIV transmission; antiretroviral therapy; mode of delivery
