Virologic Response to NNRTI Treatment among Women Who Took Single-dose Nevirapine 18 to 36 Months Earlier
A Coovadia1, B Marais1, E Abrams2, G Sherman3, G Barry1, S Hammer2, A Karstaedt4, J Walter2, T Meyers4, and Louise Kuhn*2
1Coronation Hosp, Johannesburg, South Africa; 2Columbia Univ Mailman Sch of Publ Hlth, New York, NY, US; 3Univ of the Witwatersrand Med Sch, Johannesburg, South Africa; and 4Chris Hani Baragwanath Hosp, Johannesburg, South Africa
Background: A study in Thailand observed that women prescribed
nevirapine (NVP) for prevention of mother-to-child
HIV transmission (PMTCT) were less likely to achieve virologic
suppression when treated with a non-nucleoside reverse transcriptase inhibitor (NNRTI)-regimen
than unexposed women. Many studies have detected NNRTI-resistance mutations
frequently 4 to 8 weeks after single-dose NVP used for PMTCT. However, as time
elapses, mutations are detected less frequently, suggesting that effects of single-dose
NVP exposure on treatment response may decline as time passes after exposure.
We are testing whether prior exposure to single-dose NVP >18 months earlier
would still increase the likelihood of virologic
failure among women treated with an NNRTI regimen.
Methods: We are conducting a non-experimental clinical trial
in Johannesburg, South Africa, to examine virologic response to treatment with NVP/lamivudine/stavudine among women exposed to single-dose NVP
18 to 36 months earlier compared with unexposed women with prior live births in
the same interval. We have results to date on 60 exposed and 30 unexposed women
who have had the opportunity to be followed to at least 12 weeks post-treatment.
All women meet eligibility criteria for antiretroviral treatment (CD4
count<200 or stage III+, and CD4 <350) and have viral load measurements
(Roche v1.5 ultra-sensitive) performed every 4 weeks to 24 weeks, and then
every 12 weeks thereafter to 96 weeks post-treatment.
Results: Pre-treatment among NVP-exposed women (median
26 months post-single-dose NVP), the median viral load was 93,325 copies/mL and CD4 count 138 cells/mL; among the unexposed, 199,526
copies/mL, and CD4 count 167. Age, parity, education,
clinical stage, weight, and other clinical and social characteristics were
similar. By 24 weeks on treatment, all 38 (100%) NVP-exposed women had a viral <50
copies/mL (1 woman, who switched from NVP to Kaletra because of liver toxicity, is included; 2 women
lost to follow-up within 2 weeks are excluded. Of the 20 remaining women, 15
(75%) still reached 24 weeks and had <50 copies/mL
when last seen. Among the unexposed, 13 of 17 (76%) women had a viral load <50
copies/mL by 24 weeks (4 women [2 failures] switched
from NVP due to liver toxicity  or severe rash  are included, 1 lost to
follow-up is excluded; 9 of 12 [75%] remaining women had <50 copies/mL when last seen).
Conclusions: We observed excellent virologic
response to NNRTI-based treatment among women exposed to single-dose NVP >18
months supporting NNRTI-based treatment regimens as effective options for this
group of women.