Journal of Acquired Immune Deficiency Syndromes (08.01.03)
Worldwide, sexual contact is the major mode of HIV
transmission among adults. Citing a lack of data on sexual
behavior in HIV-infected individuals on potent antiretroviral
therapy, the authors evaluated the sexual behavior of
individuals in the Swiss HIV Cohort Study. In particular, they
looked for associations between unsafe sex and optimal viral
On April 1, 2000, researchers introduced a new questionnaire
into the SHCS, a prospective cohort study of HIV-infected
individuals 16 and older. The cross-sectional study included
all SHCS participants who responded to the new questionnaire
for the first time within 12 months of its introduction.
Answers to survey questions - on protected or unprotected
sexual intercourse, type of partnership (stable or
occasional), known or unknown serostatus of a stable partner,
and whether patients lived alone, with relatives or partners,
or in institutions - were voluntary and anonymous.
The scientists gathered clinical and demographic information
prospectively within the framework of the SHCS. They measured
viral load using the Roche Amplicor Monitor assay, with the
modification for ultrasensitive detection. They defined
optimal viral suppression as plasma HIV-1 RNA levels of <50
copies/mL at every cohort visit during the 12 months preceding
the date of completing the sexual behavior questionnaire.
"Our primary hypothesis," the researchers wrote, "was that
self-reported unsafe sexual behavior would be more prevalent
among individuals with optimal viral suppression, because they
would perceive themselves as unlikely to infect a sexual
Of the 4,948 individuals registered with SHCS on April 1,
2000, 4,723 (95 percent) responded to the sexual behavior
questionnaire. Fifty-five percent of respondents had a stable
partnership and 19 percent had occasional partners during the
previous 6 months. Six percent had both types of partners.
Eighty-two percent of subjects with stable partners reported
intercourse, and 76 percent of those said they always used
condoms. Of individuals with occasional partners, 87 percent
reported sexual intercourse; 86 percent of those said they
always used condoms.
"Overall," the authors wrote, "12 percent of the individuals
reported unsafe sex, 81 percent denied unsafe sex, and the
remaining 7 percent neither reported nor denied unsafe sex. Of
those individuals who responded, 78 percent received
antiretroviral therapy, and 25 percent had optimal viral
suppression with viral loads of <50 copies/mL during the
preceding 12 months.
"In multivariate analysis," they continued, "reported unsafe
sex was not associated with optimal viral suppression,
antiretroviral therapy, diagnosis of an AIDS-defining disease,
or education. However, reported unsafe sex was associated with
gender, age, ethnicity, HIV transmission group, HIV status of
the stable partner, having occasional partners, and living
The researchers found that individuals with HIV-infected
stable partners, from ethnic groups other than white, and
those with occasional partners were more likely to report
unsafe sex. Males, individuals 41 or older, and subjects
living alone were less likely to report unsafe sex.
"In conclusion," the researchers wrote, "the present study
underlines the importance of epidemiologic data on sexual
behavior in HIV-infected populations. In the SHCS, 4 of 5 HIV-
infected individuals report safer sexual behavior with their
partners. Individuals receiving potent antiretroviral therapy
and those with optimal viral suppression do not seem more
likely to engage in unsafe sex. However, unsafe sex is more
likely in some subgroups of individuals with HIV infection.
Sexual health programs targeting these subgroups should
complement programs aimed at the general population."