Awareness and Interest in HIV Pre-Exposure Prophylaxis Among Street-Based Female Sex Workers: Results from a US Context

Introduction

In the United States, heterosexual women account for about 19% of new HIV infections. ¹ Globally, female sex workers (FSW) have an elevated risk of HIV that is 13.5 times that of similarly aged women who do not sell sex. Despite documented high rates of HIV internationally, ^{2 –4} little research in the United States has focused on HIV among FSW. One large (n = 8473) surveillance study of heterosexual women at high risk of HIV infection reported that 16.6% of the sample sold or traded sex in the past year; HIV rates were higher among women who traded sex (3.7%) compared with women who had not traded sex (2.5%). ¹

Structural vulnerability theory can help to understand—at least partly—why this HIV disparity may exist for FSW. Structural vulnerabilities exist when an individual or group's position in society constrains behavior due to conflict with existing power structures, elevating risk of negative health outcomes, and health disparities at a population level. ⁵ The illegal nature of sex work in many countries contributes to sex work stigma and health outcomes that are associated with structural vulnerability, including elevated rates of client violence, ⁶ police-related harassment and violence, ⁷ and drug use ^4,8,9 Structural vulnerabilities and their associated negative health outcomes can increase stigma related to sex work, serving as a barrier to HIV testing or treatment. ^10,11 Given the complicated nature of structural vulnerabilities and elevated risk of HIV among FSW, women-controlled HIV prevention methods are critical for FSW.

The development and early success of pre-exposure prophylaxis (PrEP) provides a biomedical opportunity in HIV prevention. To date, there have been 13 PrEP trials that have included women, 4 of which have included and reported data for FSW. ^{12 –15} Two trials found low effectiveness of PrEP, in part reflecting low adherence rates; ^12,15 however, two other studies of PrEP found that it is effective at HIV prevention given adherence ^13,14 Simulated models from South Africa suggest that the addition of PrEP to current condom distribution and HIV testing and treatment efforts in the country could reduce HIV incidence among FSW and clients by 40%. ¹⁶ Recognizing its potential in this population, clinical guidelines from the Centers for Disease Control and Prevention (CDC) list commercial sex work as an indicator for PrEP prescription among heterosexual women ¹⁷ PrEP is a unique innovation that gives FSW control over their HIV risk even in the face of many HIV prevention challenges.

Despite its promise, there is relatively little information about PrEP awareness or interest in the FSW population. Prior studies in China, ¹⁸ Kenya, ¹⁹ and Mexico ²⁰ have found that although awareness of PrEP among FSW is low, interest is high. A study of street-based FSW (N = 60) awareness and interest of PrEP in Baltimore, MD echoed these findings. ²¹ That was, to our knowledge, the only prior study of PrEP attitudes among FSW in the United States, though a study of women accessing care at reproductive health clinics in Baltimore found that a history of selling sex was the most significant factor in PrEP interest ²²

Similarly, studies of PrEP attitudes among people who inject drugs and men who have sex with men (MSM) found that a history of sex work was a key factor associated with PrEP interest. ^23,24 Prior research has also found that experiencing intimate partner violence was an important factor in decreased interest in PrEP among FSW ²² but experiencing violence from clients was associated with increased interest. ²¹ In qualitative interviews, FSW associated PrEP with feelings of empowerment. ²⁵ Research must expand to consider social and behavioral factors that are associated with PrEP use and attitudes among FSW in the United States, given the CDC prescription recommendation and the unique structural vulnerabilities that FSW experience.

Much of the literature on PrEP in the United States focuses on MSM, and it provides insights into awareness and attitudes about PrEP for other HIV high-risk vulnerable populations. Literature has found low awareness of PrEP but high interest among both MSM ^{24,26 –28} and “high risk” heterosexual women, among whom FSW are included. ^25,29 From qualitative data of “high risk” heterosexual women in six U.S. cities, women expressed frustration at not hearing about PrEP before enrolling in the study given its possibilities as an HIV prevention tool. ²⁵ Finally, literature about PrEP awareness and use among MSM shows that access to HIV testing services can be an important context for learning about PrEP. ^{24,26 –28}

To address the gaps in the literature, this study examines the demographic, behavioral, and interpersonal factors that are associated with awareness and interest in daily oral PrEP (termed hereafter as PrEP) among a cohort of HIV-negative street-based cisgender FSW in Baltimore, MD. These data were collected as part of the Sex workers and Police Promoting Health in Risky Environments (SAPPHIRE) study.

Methods

Results

Discussion

This is one of the first studies of awareness and interest in PrEP among FSW in the United States, with one of the largest FSW cohorts to date. We found that although awareness of PrEP was low, interest in PrEP was high, particularly among women who were characterized by structural vulnerability, which directly heightens their risk for HIV. Our results show that FSW who had experienced social and environmental HIV prevention challenges, including client condom coercion and moving to unfamiliar areas to sell sex due to the police, are more likely to be interested in PrEP.

Hearing about PrEP was relatively rare, though two-thirds of women were interested in taking PrEP on learning about it, suggesting that current PrEP education and outreach efforts are not reaching this population that meets a CDC criterion for PrEP prescription. The Health Department is conducting two CDC-funded public education campaigns in Baltimore that aim at expanding knowledge of and accessing PrEP ³⁵ that target MSM and transgender people. Although it is possible that some FSW are aware of PrEP because of this city-wide campaign, the campaigns are not targeting this population and the campaign messages may not be impacting FSW risk perception. ³⁵ Despite this ongoing education effort, FSW in our sample in Baltimore are still widely unaware of PrEP.

In adjusted models of PrEP awareness, condom coercion with clients and condomless sex with an intimate partner were significantly associated with lower PrEP awareness. These findings underscore the overall importance of reaching the most vulnerable women—including those who are at heightened risk of abuse, violence, and victimization—as part of efforts to increase PrEP awareness among this key population. Prior research has found unique benefits of PrEP use among women who are subject to abuse from intimate partners, including discreet use without partner awareness and dual protection for women who also inject drugs, a significant sub-group of our sample of FSW. ³⁶ Our findings lend support for extending these benefits to HIV protection from client-perpetrated violence. FSW who were unaware of PrEP may be a particularly vulnerable population of women and, therefore, one of the most critical groups in need of PrEP education and outreach.

Our results also suggest that FSW may be interested in taking PrEP once aware of its availability, similar to other studies of FSWs. ^{18 –21} Ease of taking PrEP was the most significant association with interest in PrEP in adjusted models. This is self-reported ease of hypothetically taking PrEP, and further research will be required to understand the reality of PrEP adherence for women. We also do not know the extent to which women are considering the contextual factors around daily PrEP management; the wording of the question may lead women to only consider the isolated act of taking a pill and not the circumstances by which one acquires PrEP. However, our findings suggest that there is a group of FSW for which there is high motivation and willingness to take PrEP and that there are health care settings that may be natural fits for intervention implementation such as a clinic or needle exchange. Nearly half the sample reported seeing a doctor or using the needle exchange in the past 3 months, which are encouraging findings for future PrEP intervention contexts. The full potential of PrEP, particularly among vulnerable populations such as FSW, relies on strong and ongoing patient–provider interactions and may be the most useful to these populations when linked to other clinical and outreach services. ³⁷ However, our findings raise concerns about the implementation of interventions as clinicians working with high HIV risk populations should already be aware of CDC PrEP prescribing guidelines; previous studies of physicians in a variety of health care settings have documented a similar disconnect between PrEP-eligible patients and physicians. ^{38 –40}

Future interventions for improving physician awareness of PrEP should consider improving physician-related factors and improving PrEP screening and prescription through enhanced workflow. Physician-related factors may include increasing provider knowledge about PrEP, particularly among generalists, and facilitating communication between physicians who had positive experiences providing PrEP to FSW and physicians who had not prescribed PrEP to disseminate information and provide guidance about important clinical considerations for this population. ³⁸

Prior research has also demonstrated the effectiveness of an HIV risk score that is generated through electronic medical records of emergency department patients, alerting providers to PrEP eligibility. ³⁹ Future research will need to validate these findings, but this intervention holds promise to improve workflow and provider awareness of PrEP in a busy environment such as the emergency department (where more than half of our sample recently sought care.).

HIV-related vulnerabilities were significantly associated with PrEP interest, including responses to police activity and gonorrhea and chlamydia infection. Clinically significant PTSD symptoms were significantly associated with an increase in PrEP interest, an encouraging finding given established associations between poor mental health and challenges to primary HIV prevention. ^{41 –43} Moving to an unfamiliar area to work to avoid the police was also significantly associated with greater interest in PrEP. Familiar areas to sell sex provide FSW more control over the services they provide and their risk for violence, particularly in street-based sex work where women often have less control over these HIV risks compared with venue-based sex work locations. ^{44 –46} Moving to unfamiliar areas to work can upend these safeguards and heighten the HIV risk environment for FSW because they are not as familiar with their work environment.

Results related to gonorrhea or chlamydia infection and PrEP interest were not in the expected direction: Women with a gonorrhea or chlamydia infection were less likely to be interested in PrEP. Given that STI infection can be an occupational hazard of sex work, it is not clear from the data whether STIs are a driver of diminished interest in PrEP by itself or whether STIs are correlated with more salient factors that drive PrEP interest such as more frequent sex work or condom coercion. STIs may be an indicator of the most structurally vulnerable women who have more immediate priorities than STI or HIV risk reduction. More research is needed to understand the relationship between STIs, vulnerability, PrEP interest, and potential uptake.

We found several marginally significant associations between PrEP interest and frequency of sex work and adverse experiences from clients and police. We found that women who may have less agency in making choices to engage in HIV prevention behaviors—such as FSW experiencing client condom coercion, more frequent sex work, or police harassment—also expressed more interest in PrEP than women who do not face similar structural constraints. Structural vulnerabilities constrain FSW agency over behaviorally based HIV prevention—such as condom use with clients or having safe locations to bring clients—but PrEP provides a unique opportunity for FSW to assert agency in HIV prevention. Similar results were echoed in prior literature about PrEP providing an opportunity for empowerment and agency in HIV prevention. ²⁵

These results should be considered in light of several limitations. First, although we assessed awareness of PrEP, we did not ask about the extent of women's knowledge of PrEP. It is possible that the proportion of women in the sample who had full knowledge (rather than a passing awareness) of PrEP may be even lower than current results. Second, this sample comprised only street-based FSW in Baltimore and conclusions cannot be drawn about FSW in other contexts (i.e., brothels, exotic dance clubs) or geographic areas. Third, the study is cross-sectional, making the temporal relationship between variables difficult to determine. Finally, it is possible that because of the CAPI survey format and a social desirability bias, women may have underreported answers to sensitive questions.

This study—one of the first to examine PrEP attitudes among FSW in the United States—demonstrates high interest in PrEP among street-based FSW, despite low awareness. Results suggest that women may recognize important HIV prevention challenges in their lives; women-controlled methods such as PrEP may mitigate these challenges and provide women with agency in HIV prevention. Efforts should be made to raise awareness of PrEP in this population and for clinicians and public health professionals to consider and help mitigate a woman's challenges to and motivations for PrEP uptake in a clinical setting.