Interpreting Gaps Along the Preexposure Prophylaxis Cascade and Addressing Vulnerabilities to Stigma

In this issue of AJPH, Shover et al. (p. 1408) illuminate disparities in preexposure prophylaxis (PrEP) uptake among nearly 20 000 sexual- and gender-minority individuals seeking sexual health services. This study is of exceptional value because of the size and diversity of the sample, which includes sexual- and gender-minority groups underrepresented in existing literature. The disparities identified by the researchers support the conceptual model they present, which expands current PrEP cascade models by incorporating demographic and behavioral characteristics as direct and indirect predictors of PrEP initiation.

While I recognize the empirical and conceptual importance of this work with respect to understanding PrEP uptake, I question the significance of the other PrEP-related constructs examined—PrEP eligibility and perceived candidacy—and the interpretation of discrepancies among PrEP eligibility, perceived candidacy, and use. In addition, given the vulnerability of the authors’ conceptual model to stigma, I suggest a reconfigured version as an aspirational framework for future PrEP implementation.

INTERPRETING CASCADE GAPS

Shover et al. report that 70% of patients were eligible for PrEP, 37% perceived themselves as candidates for PrEP, and 10% were currently using PrEP. Initially, these discrepant values may register as alarming gaps along the PrEP cascade indicative of unmet need. Indeed, the researchers conclude that these gaps merit targeted intervention. However, such a conclusion may be premature in the absence of other contextual information and upon further scrutiny of PrEP eligibility and perceived candidacy as precursors to PrEP uptake.

In the study by Shover et al., the lack of contextual information surrounding the finding that only 10% of patients used PrEP obscures the nature and magnitude of intervention needed. Drop-offs from one stage to the next within a PrEP cascade are not inherently problematic. Our public health mission is not to ensure that every person at risk for HIV uses PrEP but rather to ensure that every person is informed about and offered access to PrEP. Previous PrEP awareness, desire for PrEP, and access to PrEP were not reported; consequently, we cannot infer the extent to which nonuse reflects informed patient decision-making versus systematic constraints in PrEP knowledge and access warranting intervention.

Eligibility and perceived candidacy offer limited value as objective indicators of PrEP demand or as targets for PrEP uptake. Within this study, PrEP eligibility was operationalized as having had a sexually transmitted infection in the past year or condomless anal intercourse in the preceding three months. As have other eligibility criteria,^1,2 these criteria failed to reliably identify people who could benefit from PrEP. Specifically, 18% of study patients who newly tested HIV-positive at the time that eligibility was assessed were deemed ineligible by the criteria. In addition, even though 100% of patients were recruited and interviewed at a time when they were seeking testing for HIV and other sexually transmitted infections, an act often prompted by potential exposure, 30% were deemed ineligible for PrEP. It is also noteworthy that 11% of current PrEP users were ineligible, further demonstrating that preset criteria do not capture all individuals who derive benefit from PrEP. The finding of social disparities in PrEP eligibility provides additional incentive to reexamine present applications of preestablished eligibility criteria.

Perceived PrEP candidacy (conceptualized by Shover et al. as perceived need) may be an important component of patients’ decision-making process, but it is shaped by preexisting knowledge and beliefs about HIV and PrEP. In the study, patients were asked, “Do you believe that you are currently an appropriate candidate for PrEP?” Background information presented before this question and patients’ preexisting knowledge (if any) were not specified. Without operationalizing “appropriate candidacy” for patients, the reported misalignment between eligibility and perceived candidacy is unsurprising: Patients were unlikely to be using the same criteria for assessing their candidacy as those selected by the researchers to represent eligibility. The finding that 65% of PrEP-inexperienced patients deemed eligible for PrEP by the researchers’ criteria did not perceive themselves as appropriate candidates for PrEP may suggest that patients underestimate their risk, emphasizing a need for patients to be educated about HIV and PrEP before being asked to assess their own candidacy. Alternatively, this discrepancy may offer additional evidence of the inability of preestablished eligibility criteria to accurately discern prospective PrEP benefit. That 11% of current PrEP users did not regard themselves as “appropriate candidates” for PrEP may suggest that some PrEP users see themselves as unique from most PrEP users, perhaps because of negative stereotypes.

In summary, additional contextual information is needed to ascertain the significance of low overall PrEP uptake and to optimally address uptake disparities. The incongruity among PrEP eligibility, perceived candidacy, and use may not be cause for concern or intervention with respect to potential PrEP users; rather, it may be reason to reconsider the value of PrEP eligibility and perceived candidacy as proxies for potential PrEP benefit and to reevaluate their positioning within PrEP cascade models.

ADDRESSING STIGMA VULNERABILITIES

As stated previously, Shover et al. present a conceptual model that expands existing cascade models by incorporating demographic and behavioral factors likely to influence PrEP eligibility, perceived candidacy (need for PrEP), and PrEP initiation (reproduced as Figure 1a). Within the model, they also introduce alternate pathways to PrEP initiation through the offering of PrEP by a provider. A striking aspect of their model is the vulnerability of nearly every pathway in the model to stigma, which may explain some of the disparities they document. Although assessment of disparities in providers’ offering of PrEP based on patients’ demographic and behavioral characteristics was beyond the scope of their study, previous research has documented differences in PrEP prescription across demographic and behavioral subgroups of patients³ and the potential for social biases and sexual values to systematically influence providers’ willingness to prescribe PrEP.^4–6 These and other manifestations of stigma in the pathways to PrEP initiation are particularly relevant to many key populations with disproportionately high HIV incidence, who often face multiple, intersectional forms of stigma.

FIGURE 1—

Conceptual Models of Preexposure Prophylaxis (PrEP) Initiation (a) as Originally Presented and (b) Reconfigured

Note. The original model (shown in panel a) by Shover, et al. (p. 1410) highlights the direct and indirect impact of demographic and behavioral characteristics on PrEP initiation. Nearly all pathways leading to PrEP initiation are vulnerable to stigma. The reconfigured model (shown in panel b) may improve PrEP access and equity within health care settings. The reconfigured model rearranges existing elements in the model by Shover et al. and is not intended to capture other factors (e.g., additional patient decisional influences) not originally represented.

The model presented by Shover et al. likely reflects the current state of PrEP implementation in many settings and underscores the need to adopt new implementation strategies less susceptible to stigma. In Figure 1b, I present a rearrangement of the core elements of the model as an aspirational framework for future implementation within health care settings. The framework universalizes PrEP education, eliminates several pathways with identified vulnerabilities to stigma, and explicitly positions the patient as central decision-maker. Eligibility for PrEP, as defined by preestablished sexual history criteria, is replaced by provider input and repositioned to support patient decision-making.

CONCLUSIONS

The study by Shover et al. offers essential insight into patterns of PrEP uptake and uptake disparities in a large, diverse, sexual- and gender-minority sample. Their conceptual model highlights demographic and behavioral characteristics as important drivers of PrEP uptake and exposes multiple pathways via which stigma could compromise PrEP uptake for socially marginalized groups. Follow-up investigation is vital to understanding intervention needs and the extent to which stigma underlies observed disparities. Nonetheless, a universalized approach to PrEP education that gives all care-engaged individuals the opportunity to make informed decisions about whether PrEP is right for them can help to guard against the possibility that implementation practices within health care settings contribute to disparities in access.⁷