UCSF researchers have found that HIV-infected homeless and marginally housed
people who have trouble sticking to their antiviral regimens may temporarily
delay the onset of full blown AIDS if they manage to take at least half of
their anti-HIV medications.
The UCSF study, published in the June 1, 2001 issue of AIDS, found that only 8
percent of the patients who took between 51 percent and 90 percent of their
antiviral medications over the 13 months of follow-up progressed to AIDS.
Progression to AIDS is defined as a decline in CD4 cell count to below 200
cells or the development of an opportunistic infection. None of the study
participants who took 90 percent or more of their medications progressed to
AIDS during the follow-up period. Of those who took 50 percent or less of their
medications, 41 percent progressed to AIDS.
“This study shows that adherence to medication regimens is not only closely
related to viral suppression, but also disease progression. Yet we were
surprised that very few of the patients with moderate levels of adherence, in
the range of 50-90 percent, developed AIDS. These levels of adherence are too
low to achieve durable viral suppression in most people,” said the study’s lead
author, David R. Bangsberg, MD, MPH, UCSF assistant professor of medicine and
director of the Epidemiology and Prevention Interventions (EPI) Center at San
Francisco General Hospital Medical Center (SFGHMC). Bangsberg cautioned
however that the long-term benefit, specifically over decades, may be quite
different and may require higher levels of adherence.
“This study suggests that the more pills you take, the better you do,” said
study co-author Andrew Moss PhD, UCSF professor of epidemiology and medicine.
“The relationship between adherence and clinical benefit is a continuum, not an
all-or-none phenomenon. For every 10 percent increase in adherence we found a
28 percent reduction in the risk of proceeding to AIDS.”
The study assessed whether 76 HIV-infected homeless and marginally housed
individuals without AIDS who were taking anti-HIV therapy actually took their
medications. Researchers counted pills every 3 to 6 weeks at the participants’
usual places of residence to measure adherence to antiviral therapy. Thirty
two percent had low adherence; they took less than 50 percent of their
antiviral medications as prescribed. Almost half, 49 percent, had moderate
adherence (between 51 percent and 90 percent), and 20 percent took more than 90
percent of their medications as prescribed.
The levels of HIV virus in each participant’s blood was measured monthly and
their CD4 cells (the disease fighting blood cells targeted and destroyed by
HIV) were measured quarterly. The San Francisco Department of Public Health’s
AIDS Surveillance Registry was used to identify opportunistic infections not
detected by the study.
At the beginning of the study, 47 (61 percent) had never received antiviral
therapy. Subjects who had initiated antiviral therapy before the study began
had been on therapy a median of 14 months.
The study population had a high risk for non-adherence. Ninety-three percent of
the participants were homeless, 86 percent were male, 59 percent were
non-white, 32 percent had had psychiatric hospitalization, and 29 percent had a
high prevalence of recent injection drug use.
Study co-authors are Sharon Perry, statistician, and Richard A. Clark, senior
public administrative analyst, both with UCSF’s Department of Epidemiology and
Biostatistics at SFGHMC; Edwin D. Charlebois, PhD, MPH, UCSF assistant
professor of medicine at the EPI Center at SFGHMC; Marjorie Robertson, PhD,
senior scientist at the Alcohol Research Group at the Public Health Institute,
Berkeley; and Andrew R. Zolopa, MD, assistant professor of medicine at Stanford
University’s School of Medicine.
The study was funded by the National Institute of Mental Health, the
University-Wide AIDS Research Program of the State of California, the
UCSF/Gladstone Institute for Virology and Immunology Center for AIDS Research
and the Doris Duke Charitable Foundation.