Decision about mode of delivery can be safely based on viral load one month before delivery
P. Tostes Berardo Carneiro da Cunha1, E. Joao1, M.I. Gouvea1,2, L. Sidi1, E. Martins1, C. Braga1, A. Ferreira Medeiros1, P. Rabuske1, C. Bressan1, J. Menezes1, H.J. Matos1,3
1Hospital dos Servidores do Estado, Doenças Infecciosas e Parasitárias, Rio de Janeiro, Brazil, 2FIOCRUZ, Rio de Janeiro, Brazil, 3Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
Background: Measures to prevent mother-to-child transmission (PMTCT) of HIV have been very effective, with transmission rates < 1%, and appropriate management of delivery is a key component. Elective C-section is currently indicated for PMTCT in women with viral load (VL) >1.000 copies/mL because of increased transmission during vaginal labor due to contact of the fetus with maternal secretions or blood or prolonged rupture of membranes. However, C-section is associated with increased risks of maternal and infant morbidity, mainly in developing countries. Since ante-partum VL is determinant to indicate mode of delivery, a reliable time point to assess it is essential to guide the decision.
Methods: From 01/2007 to 08/2009, 179 HIV pregnant women under HAART were selected from a cohort at a center for PMTCT in Rio de Janeiro. VL was measured at weeks 34-37 to decide mode of delivery and again within 7 days pos-partum, still under HAART. Statistical analysis was performed using SPSS, v13.0. A 5% significance level was chosen. Positive Predictive Value (PPV), overall agreement, and Cohen kappa (CK) of pre-delivery cut-off of < 1000 copies for VL were calculated in relation to immediate post-delivery VL cut-off of < 1000 copies.
Results: When cut-off values of < 1000 for immediate post-delivery VL were concerned, < 1000 cut-off pre-delivery values had a PPV of 93.8 % (CI 95% 89.5-98.1), for a prevalence of 84.4% (CI 95% 78.7-89.9) of women with immediate post-delivery VL < 1000 copies. The overall agreement of pre-values and post-values was 86.6%, and the Cohen kappa was 0.55 (CI 95% 0.38-0.7). The median interval between pre-delivery VL and delivery was 29.5 days.
Conclusions: VL measured one month pre-delivery can predict VL control at delivery in 93.8% and obstetrical decision about mode of delivery can be safely based on that value.
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