GENEVA, Switzerland--In the first study of its kind, a team of San Francisco AIDS specialists has conducted a systematic review of individuals who seek out Post-Exposure Prevention (PEP) treatment following a possible exposure to HIV. The researchers--from the University of California San Francisco and the San Francisco Department of Public Health--looked at giving potent anti-HIV medications and intensive counseling to people possibly exposed to HIV by a sexual activity or intravenous drug use.
James O. Kahn, MD, associate professor of medicine in the UCSF AIDS Program at San Francisco General Hospital, presented PEP study findings here today (June 30) at the 12th World AIDS Conference.
The ongoing study focuses on the conditions that cause people to come to a PEP clinic, the decisions they make about their options, and how they fare. The idea of giving anti-retroviral drugs to someone possibly exposed to HIV is not new. These drugs have been prescribed for the past 10 years to health care workers who suffer accidental needle sticks, with the thought that HIV infection could be stopped before it has a chance to spread in the body. "Our study is the first to describe a number of fundamental aspects of PEP," said Kahn. "We know some doctors are prescribing anti-retroviral therapy for HIV exposure to their patients, but they are not collecting the vital data needed to understand the implications of having PEP available to all individuals in the community."
"For example, we need to know what type of exposures cause people to seek information about PEP, which individuals choose to take medications, how patients adhere to the month-long treatment, what side- effects develop, and how people's risk-taking behavior changes after taking PEP and receiving our intensive counseling," Kahn said.
The study began in November 1997 and is being conducted at three sites in San Francisco. To date, 151 patients have enrolled in the study. "This field is in its infancy. No one is 100 percent certain that anti-retrovirals given within 72 hours of exposure to HIV will prevent infection, but there is considerable evidence that suggests that it will," said co-investigator Jeffrey Martin, MD, MPH, UCSF assistant professor of medicine, and epidemiology and biostatistics, who will present further findings on July 1 regarding PEP treatment.
"This study is not testing whether PEP works per se, but it is looking at who is interested in receiving medications We feel it is essential to understand the demand for the drugs and some of the consequences in prescribing them," he said. When patients with possible exposure to HIV show up at one of the three study-sponsored clinics in San Francisco, they are tested for HIV, counseled about their risk, and advised on the pros and cons of the PEP drugs. The most common regimen is two drugs given for four weeks along with risk reduction counseling. The patients are tested at four weeks, again at six months, and at one year for the development of HIV infection.
Whenever possible the counselors try to have the exposed person bring in his or her partner for testing so that the risk of HIV exposure can be known for sure. "There was some concern that having PEP as an option might discourage safe sex practices," said Martin. "So far, however, we have only found a handful who are repeatedly coming in. And the fact that they are coming in gives us access to these high-risk takers who are not heeding other safe sex messages."
Since the beginning of the study last November, findings include:
- The exposures were almost all sexual, with anal intercourse being the most common. Only one person has sought PEP following exposure through shared drug equipment.
- About half of the patients knew their partners were HIV-infected. Forty-three percent didn't know for sure but knew their partners had one or more risk factors, such as intravenous drug use or being a man who has sex with men. The remainder were unsure about their partners' HIV status or behavioral history.
- All but six subjects elected to receive medications, although it is not a criterion for study enrollment. These six are receiving risk reduction counseling and are being monitored for HIV infection.
- Nine patients have returned for repeat PEP treatment. The investigators are studying these individuals in detail to determine reasons for their repeated exposures.
- Thus far, no one has become infected after the 28 days of treatment.
- The patients were 84 percent male and about 30 percent of them are non-Caucasian. While most participants have come from San Francisco, almost 30 percent have traveled from outside of the city to seek PEP.
- The average time after exposure and coming to the clinic is 58 hours.
Study principal investigator is Thomas Coates, PhD, UCSF professor of medicine, epidemiology and biostatistics and director of the UCSF AIDS Research Institute (UCSF ARI). Co-investigators are Michelle Roland, MD, and Margaret Chesney, PhD, both of UCSF; and Joshua Bamberger, MD, MPH, and Mitchell Katz, MD, director, both of the San Francisco DPH.
The study is supported by the National Institutes of Allergy and Infectious Disease of the National Institutes of Health, Glaxo-Wellcome, Bristol Myers Squibb, Agouron Corporation, and Chiron Corporation. The UCSF ARI is an institute without walls that encompasses all UCSF AIDS programs under a single umbrella. The ARI includes a dozen research institutes, a wide range of clinical, behavioral science, and policy programs, and nearly 1,000 investigators.