Paper # 896 
When Should HAART Be Initiated in Pregnancy to Achieve an Undetectable Viral Load?
P Read1, P Khan2, S Mandalia3, U Harrisson3, C Naftalin4, Y Gilleece4, D Hawkins3, J Anderson2, Graham Taylor*5, A de Ruiter1, and the London HIV Perinatal Res Group
1Guy’s and St Thomas’ NHS Fndn Trust, London, UK; 2Homerton Univ Hosp NHS Fndn Trust, London, UK; 3Chelsea and Westminster Hosp NHS Fndn Trust, London, UK; 4Brighton and Sussex Univ Hosps NHS Trust, UK; and 5Imperial Coll London, UK
Background: HAART has dramatically reduced HIV
mother-to-child transmission (MTCT) allowing vaginal delivery if the viral load
is low or undetectable. However, the optimum timing of HAART initiation has not
been established. This study aims to provide data for the timing of short-course
HAART in pregnancy.
Methods: Retrospective multicenter cohort study,
including all pregnant women commencing boosted PI-, NNRTI-, or triple NRTI-based
HAART. Demographics, gestation, drug class, CD4 count, and viral load results were
collated. Viral load data were right-censored at delivery date and regimen
analyses were based on an intent-to-treat model. Survival curves for reaching a
viral load <50 were stratified by initial HIV viral load. Cox’s proportional
hazards regression model adjusted for demographics and immuno-virological
parameters.
Results: Of 439 pregnancies that met the inclusion
criteria, 378 had sufficient data for analysis. More than 85% of the women were
of black African origin and infected with non-B subtype. Median age at
conception was 30 years (IQR 26 to 34). Median pre-treatment CD4 and viral load
was 330 cells/mm3 (IQR 195 to 470) and 8243 copies/mL (IQR 2341 to 32,640);
246 women (65%) commenced PI-, 129 (34%) NNRTI-, and 3 (1%) NRTI-based HAART, initiated
at a median of 23.2 weeks gestation (IQR 20.4 to 26.3). Viral load was
<50 in 292 (77.3%) by delivery date (mean 38 weeks), following a median of
58 days of therapy. Pre-treatment viral load was associated with both the time
taken and the proportion achieving a viral load <50 at delivery (P <0.001)
(see the figure). A baseline viral load of <10,000, 10,000 to 50,000, 50,001
to 100,000, and >100,000 resulted in 91%, 73%, 54%, and 37% of women <50
at delivery, respectively. In multivariate analysis, the hazard ratio (HR) for a
NNRTI regimen achieving a viral load <50 compared to a PI was 0.7 (0.52 to
0.94 CI95%). However, if viral load was >10,000, 58% of PI and 66% of NNRTI
regimens achieved <50. If the baseline viral load was <10,000, gestation
at initiation of HAART did not significantly alter the probability of a viral
load <50 at delivery. With a baseline viral load of 10,000 to 50,000 the HR
for a viral load <50 reduced to 0.51 if HAART was initiated after 23.3 weeks
(P <0.01) while if viral load was >100,000, starting HAART before
20.4 weeks gave a HR of 0.2 (P <0.01) compared with 0.1 if started
after 20.4 weeks (P <0.01).
Conclusions: HAART fully suppresses low viral load (<10,000)
even when initiated late in pregnancy. If viral load is >100,000 copies,
HAART should be initiated as early as possible to have any chance of achieving
full suppression. 
|
