[Viva] Fwd: CATIE News - Early treatment reduces HIV transmission in heterosexual serodiscordant couples

Tue May 17 18:19:02 PDT 2011

---------- Forwarded message ----------
From: <mailing at mercury.catie.ca>
Date: Tue, May 17, 2011 at 1:13 PM
Subject: CATIE News - Early treatment reduces HIV transmission in
heterosexual serodiscordant couples
To: cosmictami at shaw.ca

*CATIE News - Early treatment reduces HIV transmission in heterosexual
serodiscordant couples*

The early results of a clinical trial, called HPTN 052, show that starting
treatment early can significantly reduce the transmission of HIV in
heterosexual serodiscordant couples.
Treatment as prevention

The use of antiretroviral treatment by HIV-positive individuals to reduce
their risk of transmitting HIV to their sexual partners is commonly referred
to as “treatment as prevention.” Antiretroviral treatment can reduce the
amount of HIV in bodily fluids (such as rectal fluid, semen and vaginal
fluid) of someone living with HIV and may therefore make them less likely to
transmit HIV to others during unprotected sex. The possibility of reducing
the risk of HIV transmission is one argument made to support early
initiation of HIV treatment.

Until now, the strongest evidence for “treatment as prevention” came
from *observational
studies. *These studies have involved heterosexual, serodiscordant couples
(where one partner is HIV-positive and one partner is HIV-negative). By
systematically combining the results from multiple observational studies,
researchers recently found that the overall rate of HIV transmission among
serodiscordant couples on treatment was lower than the rate of transmission
among couples who were not on treatment. Transmission rates were reduced by
66% to 84%, depending on which studies the authors included in their
analysis.

Unfortunately, with observational “treatment as prevention” studies, it is
difficult to conclude that HIV transmission was reduced as a result of the
HIV-positive partner being on treatment and not due to other factors that
researchers may not have taken into account (also known as biases). For
example, people on treatment may be more likely to use condoms regularly,
which would explain how they have prevented transmitting HIV to their
partners. Also the studies provide little information about the relative
importance of the time of initiation of HIV treatment on potential risk
reduction.
The first “treatment as prevention” trial

Last week, preliminary results from the first *randomized controlled
trial*studying “treatment as prevention”, known as HPTN 052, were
released.
Randomized controlled trials are generally considered the “gold standard” of
evidence because they minimize—but do not eliminate—the influence of
possible biases. This type of study can more confidently attribute the
reduced the risk of HIV transmission to the antiretroviral treatment.
Study design and enrolment

The HPTN 052 trial studied the effect of “treatment as prevention” among
1,763 serodiscordant couples.  Specifically, the trial was designed to
determine if starting HIV treatment very early would reduce the risk of HIV
transmission between partners in a stable, serodiscordant relationship. The
vast majority of the couples (97%) were heterosexual. All of the couples
enrolled had been in a stable relationship for at least three months prior
to enrolment (most of the couples were married). The trial took place in
several countries, including Botswana, Brazil, India, Kenya, Malawi, South
Africa, Thailand, Zimbabwe and the United States. Due to difficulties
enrolling participants in the United States, only one US couple participated
in the trial.

To be eligible for the trial, the HIV-positive partner had to meet the
following criteria at the time of enrolment:

   - test positive for HIV within 60 days of entering the study
   - not be on treatment for HIV
   - have a CD4 cell count between 350 and 550 cells/mm3
   - be willing to start treatment earlier than suggested by the treatment
   guidelines in their country

The HIV-negative partner had to have tested negative for HIV within 14 days
of entering the study.

A total of 890 HIV-positive men and their partners, and 873 HIV-positive
women and their partners participated in the study. Half of the HIV-positive
men and women started treatment immediately upon enrolment (early
treatment). The other half did not start treatment until their CD4 count
dropped to between 200 and 250 cells/mm3 or they developed an AIDS-related
illness (delayed treatment).

All couples received regular adherence counselling, HIV risk-reduction
counselling, free condoms, HIV testing, and screening for and treatment of
other sexually transmitted infections (STIs).
Preliminary results

Although the clinical trial is scheduled to be completed in 2015,
preliminary results have been released early as a result of an interim
review by an independent data and safety monitoring board (DSMB). Based on
the study data, the DSMB concluded that earlier initiation of HIV treatment
by people living with HIV substantially protects their HIV-uninfected
heterosexual partners from acquiring HIV.

Overall, 39 HIV-negative partners became infected during the study. In each
case, researchers used genetic matching to determine the source of the HIV
infection. In 28 cases, the HIV-positive partner in the study was the source
of HIV transmission. In 7 cases, the HIV-positive partner in the study was
not the source. In the remaining four cases, the sources are still
undetermined.

Researchers then looked at the 28 cases where genetic matching confirmed
that HIV was transmitted from one partner to the other within the
serodiscordant relationship. Of these 28 transmissions, 27 were among
couples where the HIV-positive partner delayed treatment and only 1 was in a
couple where the HIV-positive partner started treatment immediately.
Therefore, the study showed that earlier initiation of treatment by the
HIV-positive partner reduced the risk of transmission to the HIV-negative
partner by 96%.

The study also found that starting treatment earlier provided additional
health benefits for the HIV-positive partner. Whereas 17 cases of
extrapulmonary tuberculosis (tuberculosis that occurs outside of the lungs)
were reported among the HIV-positive people who delayed their treatment,
there were only 3 cases among the HIV-positive people who started treatment
immediately.
Limitations of the study

The vast majority of the couples enrolled in the HPTN 052 study were
heterosexual and at risk of transmission primarily through vaginal sex.
Therefore, the results may not apply to other populations—such as men who
have sex with men and injecting drug users, who are at risk of HIV infection
through other routes, including anal sex and sharing needles.

The study also does not tell us about the effectiveness of earlier treatment
at reducing the risk of heterosexual transmission in a “real-world” setting.
The participants in this trial were provided with a comprehensive package of
prevention services, including HIV risk-reduction counselling, adherence
counselling, and screening for and treatment of STIs. It is possible that
HIV treatment may be less effective at reducing transmission in the absence
of these services. For example, “treatment as prevention” may be less
effective if the HIV-positive partner does not adhere to their medications,
if either partner has other sexually transmitted infections, or if a couple
engages in more risky behaviours because they feel that the treatment
protects them fully from transmission.

Finally, the trial involved people who had recently received an HIV-positive
test result and who had relatively high CD4 counts. This suggests that the
HIV-positive people in this study are more likely to be recently infected
with HIV. Therefore, it is hard to tell from the data that is currently
available if the reduction in HIV transmission as a result of early
treatment seen in this trial would apply to other stages of HIV infection.*
*

Additional results and analysis are expected from the study at the
International AIDS Society 2011 Conference in July. These results will
include further information on risk behaviour, viral load, sexually
transmitted infections and pregnancies.
For more information

Treating HIV-infected people with antiretrovirals protects partners from
infection. Findings from NIH-funded International
Study.<http://www.niaid.nih.gov/news/newsreleases/2011/Pages/HPTN052.aspx>National
Institutes of Health, 2011 May 12.

Antiretroviral therapy for prevention of HIV transmission in HIV-discordant
couples (review). <http://www.ncbi.nlm.nih.gov/pubmed/21563172> Cochrane
Database of Systematic Reviews, 2011 May 11.

Treatment as Prevention: We’ve all heard about it but what does it really
mean?<http://www2.catie.ca/en/pif/winter-2010/treatment-prevention-we-ve-all-heard-about-it-what-does-it-really-mean>
*Prevention in Focus*, 2010 Spring.

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Meegwetch/Thank you/Merci
*Tami M. Starlight*
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