To the Editor:
The use of preexposure prophylaxis (PrEP), initiating antiretroviral medication before engaging in high-risk activity, has been suggested as a potential biomedical intervention to prevent HIV infection. However, PrEP remains an unproven intervention.1 Currently the safety and efficacy of daily use of either tenofovir alone or in combination with emtricitabine for PrEP to prevent HIV infection is being evaluated in randomized, placebo-controlled trials among injection drug users, heterosexual men and women, and men who have sex with men (MSM).2,3 Results from a clinical trial in Ghana showed that there were no significant adverse events among women taking daily tenofovir compared to placebo.4 The earliest efficacy results of these trials will be available in 2007. Despite the lack of efficacy data in humans, there were press reports in 2005 that PrEP use was already occurring among HIV-negative MSM.5
Health departments and local community-based organizations conducted rapid HIV testing and collected information on HIV risk behaviors and use of prevention services at Minority Gay Pride (MGP) events beginning in 2004. Results of the 2004 surveys at 5 MGP events showed that 25% (range: 17% to 29%) of MSM reported they had heard of PrEP and 5% (range: 0% to 7%) reported that they had used PrEP.6 Because of concerns over the potential for emergence of widespread off-label use of antiretroviral medication among MSM, we analyzed survey data collected during 2005 to 2006 MGP events to monitor PrEP and postexposure prophylaxis (PEP) use among MSM and to describe the characteristics of PrEP and PEP users.
Staff from community-based organizations and state and local health departments collected information about risk behaviors and local prevention needs for men attending MGP events in 2005 (Detroit, MI; Jackson, MS; San Francisco, CA; Washington, DC) and 2006 (Chicago, IL; Charlotte, NC; St. Louis, MO). Centers for Disease Control and Prevention (CDC) staff trained local interviewers to administer the questionnaire in person using handheld computers to record responses. Interviewers stationed throughout the event location selected respondents by approaching every nth male attendee (n = number from 1 to 10, depending on the estimated event size) who crossed a specified point at the event. In addition, men who approached interviewers and men who were waiting to be tested for HIV were selected. All selected attendees were asked to complete a brief eligibility interview. Male attendees who were ≥18 years old and who identified themselves as being of nonwhite race or of Hispanic ethnicity were eligible to participate in the survey. Persons who were unable to give informed consent (eg, because they appeared to be under the influence of alcohol or drugs) were ineligible for the survey. Noncash incentives valued at $10 or less were provided to respondents at some of the events. CDC determined MGP surveys were a public health activity, not research, and as such review by an Institutional Review Board was not required.
Local staff conducted in-person interviews to collect demographic and behavioral data and assess knowledge of antiretroviral prophylaxis to prevent HIV (PrEP or PEP) and use of PrEP or PEP to prevent HIV. Specifically, respondents were asked, 1) “Have you ever heard of people who do not have HIV taking AIDS medicines, also called antiretrovirals or AIDS cocktails, to keep from getting HIV?”; 2) “Have you ever used AIDS medicines just before engaging in a risky activity because you thought it would reduce your chances of getting HIV?”; and 3) “Have you ever used AIDS medicines right after engaging in a risky activity because you thought it would reduce your chances of getting HIV?” Respondents who were HIV-positive were also asked, “Have you ever given your AIDS medicines to a sex partner who was HIV-negative because you thought it might keep them from getting HIV?” We used SAS version 9.1 (SAS Institute, Cary, NC) to analyze respondent data and compare demographic and behavioral characteristics by knowledge of PrEP or PEP. We restricted the analysis to respondents who identified as homosexual or bisexual, or who reported at least 1 male sex partner in the past 12 months.
Of the 629 attendees who were approached by interviewers at the events and were eligible to participate, 579 (92%) agreed to participate. We excluded from the analysis 115 respondents who either did not identify as homosexual or bisexual or who did not report at least 1 male sex partner in the past 12 months. Of the 115 excluded attendees, 92 identified as heterosexual and 23 did not know or refused to answer the question about sexual identity. Among the 464 respondents included in the analysis, the median age was 32 years (range: 18 to 66 years), 361 (77.8%) were non-Hispanic blacks, 60 (12.9%) identified themselves as HIV-positive, 344 (74.1%) identified as homosexual, and 111 (23.9%) identified as bisexual.
Of the 457 MSM who responded to the question about knowledge of PrEP or PEP, 98 (21.4%) respondents had heard of people taking antiretroviral medication to keep from getting HIV. Respondents who knew about PrEP/PEP were significantly more likely to have reported being HIV-positive compared with HIV-negative or unknown HIV status (38.3% vs. 18.9%, odds ratio [OR] = 2.7, 95% confidence interval [CI]: 1.5 to 4.8). Among the 60 HIV-positive MSM respondents, 1 (1.7%) reported that he had given antiretroviral therapy to a sex partner who was HIV-negative to prevent his partner from getting HIV.
Among the 397 MSM who reported that they were HIV-negative or did not know their HIV status and who responded to the question about knowledge of PrEP or PEP, 75 (18.9%) knew about PrEP or PEP. Overall, 1 (0.3%) respondent reported taking antiretrovirals before engaging in a risky activity and 5 (1.3%) reported taking antiretrovirals after engaging in a risky activity. Of the 75 respondents not known to be HIV-positive and who knew about PrEP or PEP, 1 (1.3%) reported PrEP use and 5 (6.7%) reported PEP use. Among respondents not known to be HIV-positive, knowing about PrEP or PEP was more common among those who reported ever being tested for HIV compared to those who reported never being tested (OR = 4.9, 95% CI: 1.2 to 20.7) and among those who reported having 10 or more male anal sex partners in the 12 months before interview compared to those who reported only 1 sexual partner in the 12 months before interview (OR = 2.6, 95% CI: 1.1 to 6.2) (Table 1).
In contrast to the 2004 MGP survey, in which 5% of MSM reported ever using PrEP,6 <1% of MSM reported PrEP use in surveys conducted at MGP events in 2005 and 2006. More recent surveys conducted in San Francisco and Palm Springs, CA, by the San Francisco Department of Public Health showed that none of the 579 MSM who were interviewed reported PrEP use.7 The Palm Springs survey was conducted at a circuit party, a type of event during which some MSM may use some combination of tenofovir, sildenafil, diazepam, and 3,4-methylenedioxy-N-methylamphetamine (ecstasy), according to media reports.5,8 The results of San Francisco Department of Public Health surveys are consistent with our findings from the 2005 through 2006 MGP surveys showing that PrEP use among MSM is uncommon.
There are several possible explanations for the differences between the 2004 survey and the 2005/2006 survey results. First, respondents completed self-administered paper surveys in 2004. Respondents may have misunderstood the questions, including the definition of PrEP. In the 2005 and 2006 surveys, trained interviewers administered the questionnaire and were able to clearly define terms and answer questions from respondents. Second, the population surveyed in 2004 differed by race and ethnicity from that surveyed in 2005 and 2006, and these differences may be associated with differences in PrEP use. For example, 14% of respondents in the 2004 surveys were non-Hispanic whites. In the 2005 and 2006 surveys, non-Hispanic white respondents were excluded. However, African American respondents were more likely to report PrEP use than persons from other racial or ethnic groups in the 2004 surveys.6 Third, surveys were conducted at events in different cities each year. For example, the 2004 event in San Francisco was the main Gay Pride event, with more than 200,000 attendees. The 2005 event in San Francisco was the smaller Latino Pride. Finally, differences in sampling may account for differences in responses. A convenience sample of respondents was surveyed in 2004 and a more systematic sampling method was used for the 2005 and 2006 surveys.
Knowledge of PrEP or PEP was strongly associated with having 10 or more sexual partners in the past year compared with having 1 partner. MSM with a large number of sexual partners are at high risk for HIV, and approximately one-third of MSM with 10 or more sexual partners knew about antiretroviral medication to prevent HIV infection. However, knowledge of PrEP or PEP did not translate to widespread use of antiretroviral medication among minority MSM in our survey. MSM who were HIV-positive were more likely to know about PrEP or PEP than those who were HIV-negative or who did not know their HIV status. Although the source, type, and regimen of antiretroviral medications used by the 1 man who reported PrEP use is unknown, HIV-positive men who have been prescribed antiretroviral medication may be a source. This behavior was not common among men participating in our survey, as only 1 HIV-positive respondent reported giving medication to an HIV-negative partner to prevent HIV transmission.
Use of antiretroviral medication to prevent HIV transmission, either before suspected exposure or after suspected exposure, for which recommendations do exist,9 was low among racial and ethnic minority MSM who attended gay pride events. To monitor off-label use of antiretroviral medication before exposure among HIV-negative MSM, CDC will continue to conduct surveys of MSM behavior at MGP events. Beginning in 2007, CDC will also assess PrEP and PEP use through ongoing CDC behavioral surveillance activities.10 Until the PrEP clinical trials are completed and appropriate guidelines are developed, off-label use of antiretroviral medication for PrEP is not recommended.
Andrew C. Voetsch, PhD*
James D. Heffelfinger, MD, MPH†
Elin B. Begley, MPH†
Krishna Jafa-Bhushan, MBBS, MPH†
Patrick S. Sullivan, DVM, PhD†
*Epidemic Intelligence Service Behavioral and Clinical Surveillance Branch Division of HIV/AIDS Prevention National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention Centers for Disease Control and Prevention Atlanta, GA
†Behavioral and Clinical Surveillance Branch Division of HIV/AIDS Prevention National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention Centers for Disease Control and Prevention Atlanta, GA
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