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Slower Virologic Response in Pregnant Women Starting ART in France
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19th Conference on Retroviruses and Opportunistic Infections, March 5-8, 2012, Seattle
Mark Mascolini
Compared with nonpregnant women starting antiretroviral therapy (ART) in France, pregnant women were 40% to 50% less likely to reach a viral load below 50 copies 3 and 6 months after starting, according to results of a 900-woman study [1]. The researchers do not believe pregnancy itself explains the sluggish response rate, but their analysis could not eliminate that possibility.
People starting antiretroviral therapy usually reach a viral load below 400 copies by 3 months and a sub-50 load by 6 months, according to these investigators. But in France, one third of women starting ART during pregnancy do not have an undetectable load at delivery. The researchers planned this study to determine whether pregnancy affects early virologic response independently or treatment duration.
The analysis involved women enrolled in three multicenter prospective cohorts coordinated by the same research team. Eligible women were younger than 45, diagnosed with HIV after 2003, started ART when antiretroviral-naive either when pregnant or nonpregnant, did not start within 6 months of primary HIV infection, and did not start at or after 32 weeks' gestation if pregnant.
The researchers compared pretreatment traits and responses in 779 women who started ART during pregnancy and 113 who started when not pregnant. High proportions of women--78.4% in the pregnant group and 67.3% in the nonpregnant group--were born in sub-Saharan Africa or were not French nationals.
Pregnant women differed significantly from nonpregnant women in several ways: higher proportion with hepatitis B (10% versus 1%), lower proportion with hepatitis C (0.8% versus 4.2%), lower proportion with AIDS (1.6% versus 10.6%), lower median viral load (3.9 versus 4.4 log10 copies/mL), higher median CD4 count (355 versus 232), and higher proportion taking a ritonavir-boosted protease inhibitor (PI) (84.3% versus 61.1%) versus another regimen (1.8% versus 38.9%).
The virologic response analysis considered all women and a subgroup starting first-line ART with a ritonavir-boosted PI. One month after therapy began, about 80% in the overall pregnant group and the pregnant subgroup had a viral load below 400 copies, significantly higher proportions than in the overall nonpregnant group (61.5%) and the nonpregnant subgroup (54.8%) (P = 0.001 for both comparisons). Those response differences disappeared after 3 and 6 months of therapy.
But pregnant women were significantly less likely to have a viral load under 50 copies 3 and 6 months after starting ART in both the overall group and the subgroup starting first-line ART with a boosted PI. This analysis yielded adjusted hazard ratios (aHR) after factoring in treatment duration at months 1, 3, and 6, age, initial viral load and CD4 count, living in a couple, geographic origin, and chronic hepatitis B when starting ART:
All pregnant women versus all nonpregnant women:
Under 50 copies at 3 months: aHR 0.6, 95% confidence interval [CI] 0.4 to 0.9
Under 50 copies at 6 months: aHR 0.5, 95% CI 0.3 to 0.9
Pregnant women versus nonpregnant women starting first-line boosted PI:
Under 50 copies at 3 months: aHR 0.6, 95% CI 0.4 to 1.0
Under 50 copies at 6 months: aHR 0.5, 95% CI 0.2 to 1.0
The researchers suggested "the main factor limiting the achievement of an undetectable viral load at delivery [in France] appears to be short treatment duration." However, they did account for treatment duration in the multivariate analysis, and they noted that "we cannot completely rule out that some pregnancy-related factors may partly explain the lower proportion of [pregnant] women with a viral load below 50 copies" after 3 to 6 months of treatment.
The investigators believe their results "may suggest that ART should be started earlier in pregnant women." But they cautioned that any advantages of starting treatment earlier must be weighed against potential negative impacts on the fetus and the understanding that perinatal transmission rates are low among women with low viral loads at delivery.
Reference
1. Rachas A, Warszawski J, Le Chenadec J, et al. One-third of women beginning cART during pregnancy do not reach undetectable viral load at delivery: does pregnancy affect response to cART? 19th Conference on Retroviruses and Opportunistic Infections. March 5-8, 2012. Seattle. Abstract 1021.
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