HIV POSITIVE  Women & Children

Maternal Viral Load, Zidovudine Treatment, and the Risk of Transmission of Human Immunodeficiency Virus Type 1 from Mother to Infant


Authors: Rhoda S. Sperling, David E. Shapiro, Robert W. Coombs, John A. Todd, Steven A. Herman, George D. McSherry, Mary Jo O'Sullivan, Russell B. Van Dyke, Eleanor Jimenez, Christine Rouzioux, Patricia M. Flynn, John L. Sullivan, for the Pediatric AIDS Clinical Trials Group Protocol 076 Study Group, Stephen A. Spector, Clemente Diaz, James Rooney, James Balsley, Richard D. Gelber, Edward M. Connor


Abstract

Background and Methods: A placebo-controlled trial has shown that treatment with zidovudine reduces the rate at which human immunodeficiency virus type 1 (HIV-1) is transmitted from mother to infant. We present data from that trial showing the number of infected infants at 18 months of age and the relation between the maternal viral load, the risk of HIV-1 transmission, and the efficacy of zidovudine treatment. Viral cultures were obtained, and HIV-1 RNA was measured by two assays in samples of maternal blood obtained at study entry and at delivery.

Results. In 402 mother-infant pairs, the rate of transmission of HIV-1 was 7.6 percent (95 percent confidence interval, 4.3 to 12.3 percent) with zidovudine treatment and 22.6 percent (95 percent confidence interval, 17.0 to 29.0 percent) with placebo (P<0.001). In the placebo group, a large viral burden at entry or delivery or a positive culture was associated with an increased risk of transmission (the transmission rate was greater than 40 percent in the highest quartile of the RNA level). In both groups, transmission occurred at a wide range of maternal plasma HIV-1 RNA levels. Zidovudine reduced plasma RNA levels somewhat (median reduction, 0.24 log). Zidovudine was effective regardless of the HIV-1 RNA level or the CD4+ count at entry. In the zidovudine group, however, after we adjusted for the base-line HIV-1 RNA level and CD4+ count, the reduction in viral RNA from base line to delivery was not significantly associated with the risk of transmission of HIV-1.

Conclusions. A high maternal plasma concentration of virus is a risk factor for the transmission of HIV-1 from an untreated mother to her infant. The reduction in such transmission after zidovudine treatment is only partly explained by the reduction in plasma levels of viral RNA. To prevent HIV-1 transmission, initiating maternal treatment with zidovudine is recommended regardless of the plasma level of HIV-1 RNA or the CD4+ count. (N Engl J Med 1996;335:1621-9.)


Source Information
From the Department of Obstetrics, Gynecology, and Reproductive Science, Mount Sinai School of Medicine, New York (R.S.S.); the Statistical and Data Analysis Center, Pediatric AIDS Clinical Trials Group, Harvard School of Public Health, Boston (D.E.S.); University of Washington School of Medicine, Seattle (R.W.C.); Chiron Corporation, Emeryville, Calif. (J.A.T.); Roche Molecular Systems, Branchburg, N.J. (S.A.H.); Department of Pediatrics, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark (G.D.M.); University of Miami School of Medicine, Miami (M.J.O.); Tulane University School of Medicine, New Orleans (R.B.V.); San Juan City Hospital, San Juan, P.R. (E.J.); Agence Nationale de Recherche sur le SIDA-Hopital Necker, Paris (C.R.); St. Jude Children's Research Hospital, Memphis, Tenn. (P.M.F.); and the University of Massachusetts, Worcester (J.L.S.). Address reprint requests to Dr. Sperling at Mount Sinai Medical Center, Box 1173, 1 Gustave Levy Pl., New York, NY 10029.


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