Although clinical trials of PrEP to prevent HIV transmission among MSM are underway,6
the use of antiretroviral therapy (ART) for HIV prevention was unfamiliar in this high risk sample, yet the potential for rapid uptake of PrEP seemed highly feasible. Among this diverse sample of New England MSM, many (74%) indicated an interest in using PrEP after learning about its potential, particularly if they could obtain PrEP at no expense and if no side effects were associated with using PrEP. Corroborating findings from a study examining acceptability of PrEP use among California MSM,8
the current study found that MSM with lower educational attainment and those who knew less about PrEP and antiretroviral therapy to start with were more open to using ART for prevention once they had some information that suggested its potential as a useful intervention. More concerning, while nPEP has been recommended after high risk exposures to prevent HIV transmission for more than a decade23
and clinical experience with nPEP in high risk MSM is extensive3,4,16
the current study found that knowledge of, and experience with, nPEP was uncommon, albeit more known to MSM than PrEP.
The findings of infrequent PrEP and nPEP knowledge and use are similar to observations in other studies among MSM, though lower than one study which found 5% prior PrEP use. 8,24-26
This suggests that programs of community education are important to optimize appropriate nPEP use, and may be important if future PrEP trials indicate that antiretroviral chemoprophylaxis is effective in decreasing HIV transmission. Significantly, 35% of the MSM who had heard of PrEP reported their source of information was the media or friends, suggesting that careful and accurate reporting on the outcomes of future PrEP safety and efficacy trials is necessary to ensure proper use and understanding among MSM, particularly if PrEP studies show partial efficacy, since behavioral risk compensation could obviate modest protective benefits from these medicines. Concerns have been raised that the behavioral disinhibition associated with widespread availability of PrEP could lead to lower perceptions of risk and reduced motivations to engage in risk reduction, similar to concerns that perceptions of treatment efficacy (“therapeutic optimism”) have enhanced recent evidence of increased HIV transmission among MSM.27
In the current study, having heard of PrEP was independently associated with prior nPEP use, unprotected anal sex, crystal methamphetamine use during sex, meeting sexual partners on the Internet, higher education, and higher annual income. Yet although riskier and more affluent MSM were more likely to have ever heard of PrEP, PrEP use remained rare among this sample of New England MSM, which could reflect perceptions that antiretroviral use was associated with more potential harms than benefits. Importantly, these same variables did not predict intent to use PrEP in the future. Intentions to use PrEP in the future were not associated with behavioral risk factors (i.e., unprotected sex or drug use), but instead with less education, moderate income, no side effects from taking PrEP, and not having to pay for PrEP. Thus, if PrEP efficacy is demonstrated, community educational messages will need to be carefully tailored to present all relevant data in an easily accessible manner for MSM of diverse educational and demographic backgrounds.
In assessing willingness to use PrEP in hypothetical situations in the future, the current study found having to take more than one pill for each dose or having to take more than one dose per day were associated with modest decrease in MSM's willingness to use, and the majority still found less convenient regimens acceptable if proven to be well-tolerated and effective. This finding has implications for ensuring adherence to PrEP regimens among MSM in the future.
The present study's limitations include possible bias from socially desirable answers since the survey was interviewer administered. In contrast to traditional RDS, this study did not weight the final sample according to the population being studied, so that inferences about the prevalence of specific conditions in the population could not be assessed. This is because once we achieved our a priori determined sample size we stopped enrollment, which did not allow for recruitment chains to continue and hence interrupted the potential future state of equilibrium. As with other non-probability sampling methods, modified RDS is subject to potential biases and reduced generalizability of the study findings to the wider-MSM population. With regard to recruitment, the non-random selection of initial recruits meant that the origination of seeds could subsequently affect the characteristics of recruits. Finally, although predictors of actual PrEP use could not be assessed, analyses that evaluated intentions to use PrEP in the future is supported by the Theory of Reasoned Action/Planned Behavior,9
which has shown that intentions are a proximal predictor of a given health behavior. Moreover, the utility of this theory in predicting HIV prophylactic behavior (i.e., condom use intentions and other HIV risk taking behaviors) has been validated among a variety of populations, including MSM.28-31
These findings suggest that investigators, public health officials, and the media need to be very careful to plan programs of community education that accurately reflect the results from ongoing and future PrEP efficacy trials, and to anticipate how several key variables, including efficacy, side effect profiles, and cost are explained to at risk populations in order to ensure appropriate PrEP use if studies show partial efficacy.