UCSF study finds persons exposed to HIV infection seek early preventive treatment and adhere to medication schedules

A UCSF study has found that individuals potentially exposed to the HIV virus through sexual contact or injection drug use will, given the opportunity, seek preventive treatment within 72 hours of the exposure and will take their medications as prescribed despite side effects. The study included persons at risk for HIV infection who took advantage of the 28 day short course of anti-HIV medications known as postexposure prophylaxsis (PEP). When started within 72 hours of exposure to HIV, PEP significantly reduces the risk of viral transmission from perinatal or occupational exposures such as accidental needle sticks. PEP is currently part of treatment guidelines for perinatal and occupational exposures.

The current study, published in the March 1, 2001 issue of The Journal of Infectious Diseases, sought to discover if PEP would be feasible for sexual and injection drug use exposures to HIV.

"Our study demonstrates that you can get people to come in after they have been exposed to HIV through sexual contact or injection drug use. In fact, those with the highest risk of HIV infection will show up. We also had concerns that people might not adhere to the medication regimen, in part due to the medications'side effects. We found that these exposed persons do take their medications as scheduled and that while they often experience toxic side effects, these toxicities do not last. All in all, this is a very feasible program to implement," said lead author of the study, James O. Kahn, MD, UCSF associate professor of medicine in the Positive Health Program at San Francisco General Hospital Medical Center.

Participants in the study, which took place from December 1997 through March 1999, had to come in for treatment within 72 hours of sexual or injection drug use exposure to HIV from partners who were known or suspected to be HIV-infected. Three hundred and seventy five of the participants sought PEP due to sexual exposure. Eight came in due to exposure from sharing injection drug equipment. Four participated due to dual sexual and injection drug use exposure. Fourteen sought PEP for other traumatic exposures.

One hundred seventy four knew that their partner was HIV-infected, the other 227 were uncertain of their partner's HIV status. Three of the people who came in for PEP discovered that they themselves were HIV-infected when they took the initial HIV antibody test and were not included in the study.

The study participants were offered antiretroviral medications for four weeks. They were required to receive individually tailored HIV risk reduction counseling and antiretroviral medication adherence counseling. Participants were tested for HIV at the onset, after 4 weeks and at 26 weeks. Seventy eight percent of the participants completed the four-week antiretroviral course. Of that group, complete adherence rates, meaning they took all of their medications as scheduled, ranged from 78% to 84% depending on which antiretroviral medications they were taking. These high rates occurred despite substantial side effects from the medications.

One concern for researchers was that 39 of the study participants sought a second PEP course following a subsequent exposure within six months. Other studies are considering the issue of PEP increasing risk behavior. More intensive prevention counseling for individuals who keep engaging in high-risk behavior may be necessary, Kahn said.

Kahn observed that the prevention counseling component of PEP might support community education and prevention efforts. "The people who come in engaged in a high risk behavior that has exposed them to HIV. They're terrified and they're desperate to do something to avoid becoming HIV-infected. This gives you an entr�e at a very critical time in someone's life," he said.

None of the participants who completed the study had become HIV-infected six months following exposure. Kahn warned against reading too much into the low seroconversion rate: "In this context, four hundred and one people is not a large number. When you consider that we are usually talking about a single risky incident and that only 43% of the source partners were known to be HIV-infected, we would not have expected many people to get infected even without PEP. Yet, it is a positive indication that there may be a benefit for PEP delivered following a sexual or injection drug use exposure, similar to PEP when it is delivered to a health care worker after a needle stick or given to an HIV-infected pregnant woman to prevent transmission to her child."

Co-authors include Jeffrey N. Martin, MD, MPH, UCSF assistant professor of medicine in the department of epidemiology and biostatistics, and the Center for AIDS Prevention Studies; Michelle E. Roland, MD, UCSF assistant professor of medicine in the Positive Health Program at San Francisco General Hospital Medical Center; Joshua D. Bamberger, MD, MPH, San Francisco Department of Public Health; Margaret Chesney, PhD, UCSF professor of medicine and co-director of CAPS; Donald Chambers, PhD, specialist statistician at UCSF CAPS; Karena Franses, MSW, LCSW, associate specialist in the Positive Health Program at SFGHMC; Thomas J. Coates, UCSF professor of medicine and director of the AIDS Research Institute; Mitchell H. Katz, MD, director, San Francisco Department of Public Health.

This research was supported by grants from The National Institutes of Allergy and Infectious Disease, the UCSF Center for AIDS Research, the University of California University-wide AIDS Research Program, the William McCarty-Cooper Trust, Glaxo-Wellcome, Bristol-Myers Squibb, Agouron Corporation Inc, and Chiron Corporation.