Risk factors for detectable HIV-1 RNA at delivery among women receiving highly active antiretroviral therapy in the women and infants transmission study.

BACKGROUND

Detectable HIV-1 RNA at delivery is the strongest predictor of mother-to-child transmission. The risk factors for detectable HIV, including type of regimen, are unknown. We evaluated factors, including highly active antiretroviral (HAART) regimen, associated with detectable HIV-1 RNA at delivery in the Women and Infants Transmission Study (WITS).

METHODS

Data from 630 HIV-1-infected women who enrolled from 1998 to 2005 and received HAART during pregnancy were analyzed. Multivariable analyses examined associations between regimens, demographic factors, and detectable HIV-1 RNA (>400 copies/milliliter) at delivery.

RESULTS

Overall, 32% of the women in the cohort had detectable HIV-1 RNA at delivery. Among the subset of 364 HAART-experienced women, a lower CD4 cell count at enrollment [adjusted odds ratio (AOR) = 1.20 per 100 cells/microL, confidence interval (CI) 1.04 to 1.37] and higher HIV-1 RNA at enrollment (AOR = 1.52 per log10 copies/milliliter, CI 1.32 to 1.75) were significantly associated with detectable HIV-1 RNA levels at delivery. For the 266 HAART-naive women, both lower CD4 cell count at enrollment (AOR = 1.24 per 100 cells/microL, CI 1.05 to 1.48) and higher HIV-1 RNA at enrollment (AOR = 1.35 per log10 copies/milliliter, CI 1.12 to 1.63) were associated with detectable HIV-1 RNA at delivery. In addition, age at delivery (AOR = 0.92 per 10 years older, CI 0.86 to 0.99) and maternal illicit drug use (AOR = 3.15, CI 1.34 to 7.41) were significantly associated with detectable HIV-1 RNA at delivery among HAART-naive women. Type of HAART regimen was not significant in either group.

CONCLUSIONS

Lack of viral suppression at delivery was common in the WITS cohort, but differences by antiretroviral regimen were not identified. Despite a transmission rate below 1% in the last 5 years of the WITS cohort, improved measures to maximize HIV-1 RNA suppression at term among high-risk women are warranted.