52bLB
Reduction of HIV Transmission Risk and High Risk Sex while Prescribed ART: Results from Discordant Couples in Rwanda and Zambia
Patrick Sullivan*1, K Kayitenkore2, E Chomba3, E Karita2, L Mwananyanda3, C Vwalika3, M Conkling3, N Luisi1, A Tichacek1, and S Allen1
1Emory Univ, Rollins Sch of Publ Hlth, Atlanta, GA, US; 2Project San Francisco, Kigali, Rwanda; and 3Zambia Emory HIV Res Project, Lusaka
Background: Use of
effective ART is expected to reduce risk of HIV transmission, but concerns have
been raised that compensatory increases in sexual risk could lessen the impact
of ART provision. HIV discordant couples are an ideal group in which to study
HIV transmission.
Methods: We utilized data
from longitudinal follow-up of HIV-discordant couples in Rwanda and Zambia enrolled on or after January 2002, and followed through November 2008. ART was
initiated as clinically indicated (WHO stage III or IV and/or CD4 < 200
cells/µL). HIV– partners of infected patients were tested for HIV
and received HIV risk reduction counseling every 3 months. Data on sexual risk
were collected at each screening. We calculated an aggregate indicator of
sexual risk (self-reported vaginal sex not protected by condoms, presence of
sperm on a vaginal smear, or pregnancy). We calculated incidence density of HIV
transmission where the infected partner was on or off ART and incidence rate
ratios with 95% confidence intervals (CI), and used Cox proportional hazards
regression to estimate the impact of ART on hazard of transmission, controlling
for sexual risk as a time-varying covariate.
Results: We studied 2993
discordant couples followed for a median of 512 days: 175 HIV infections
occurred, 4 from infected partners on ART, and 171 from infected partners not
on ART. HIV incidence density on ART was 0.7%/100 person-years and off ART was
3.4%/100 person-years (rate ratio = 0.21. 95%CI 0.08 to 0.59). Couples where
the infected partner was on ART were less likely to have sexual risk (aggregate
measure) than couples where the infected partner was not on ART (odds ratio
[OR] = 0.87, CI 0.79 to 0.96) or have sperm on vaginal smear (OR = 0.65, CI
0.50 to 0.84). Hazard of infection was lower in the presence of ART (hazard
ratio [HR] = 0.21, CI 0.09 to 0.52), while controlling for the aggregate sexual
risk variable (HR = 2.7; CI 2.1 to 3.7).
Conclusions: In this cohort
of HIV discordant couples, being prescribed ART initiation was
associated with lower indicators of unprotected sex. Reduction in risk of HIV
transmission was observed when HIV+ partners were on ART; the
reduced risk was likely due to a combination of ART effects and lower risk
behaviors. Providing ARVT and appropriate risk reduction counseling to the
large number of symptomatic HIV+ Africans who still do not have
access to ART should remain a top priority.
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