Eligibility criteria for HIV pre-exposure prophylaxis (PrEP) based on behavioral markers does not capture all with biological markers for HIV risk.
Vincent Cornelisse, MD, PhD candidate
Eligibility criteria for HIV pre-exposure prophylaxis (PrEP) based on self-reported behavioral markers did not capture all of those with biological markers for HIV risk in an assessment of participants in a large PrEP distribution program in Victoria, Australia.
"Our analysis indicates that current PrEP criteria successfully capture a significant part of the population who are at risk of HIV and who may benefit from PrEP," Vincent Cornelisse, MD, PhD candidate, Melbourne Sexual Health Center and Monash University, Melbourne, Victoria, Australia told MD Mag. "However, our analysis also highlights the limitations of using such eligibility criteria, as some of the participants who did not meet PrEP criteria were nonetheless at risk of HIV."
The eligibility criteria for receiving PrEP in the PrEPX program, established to provide the prophylaxis regimen to 2600 people in Melbourne between July 2016 and April 2018, are based on criteria from the US Centers for Disease Control (CDC) guidelines. The first 4 of 6 criteria consist of self-reported behaviors that are associated with high risk of acquiring HIV, and the 5th and 6th correspond to medium risk, as determined by the CDC.
People were enrolled in the program by either meeting these criteria, or under an "exemption clause" if the clinician judged that the PrEP protective regimen would be of benefit to them.
Cornelisse and colleagues screened approximately 2000 male participants at enrollment into PrEPX for the sexually transmitted infections (STI) of syphilis, anorectal chlamydia or anorectal gonorrhea. They cite evidence to support that any of these STIs serve as a biological marker of heightened risk for HIV. The study sought to determine whether the criteria based on reported behaviors correlated with the biological marker of HIV risk in identifying those who would benefit from receiving PrEP.
The investigators reported a 10.2% incidence of newly acquired STI among the 1774 participants having STI data. There was a 7.1% incidence of STI in those not meeting eligibility criteria who were enrolled under the exemption clause. Compared with participants who were using PrEP prior to enrollment, PrEP-naїve participants were less likely to have an STI (12.3% vs 9.2%).
The odds ratio (OR) for which each eligibility criterion predicted positive STI was calculated and adjusted (aOR) for participants fulfilling multiple eligibility criteria. The aOR for criteria 1—4 ranged from 2.5 (95% Confidence Interval (CI) 1.4–4.4) to 1.8 (CI 1.3–2.5). The 5th and 6th behavior-based criteria that were associated with medium risk of contracting HIV were calculated to have aOR for positive STI of 0.8 (CI 0.6–1.1) and 1.0 (CI 0.7–1.4).
"Participants who were enrolled despite not fulfilling any PrEP eligibility criteria were found nonetheless to have a substantial prevalence of syphilis and anorectal STIs at enrollment, albeit lower than those participants who did fulfill eligibility criteria, suggesting that they were at significant risk of HIV," investigators wrote.
Cornelisse commented to MD Mag that the PrEP eligibility criteria cannot capture all possible HIV risks by the very nature of being a limited set of criteria and that the regimen should also be made available as clinical judgment indicates.
"We argue that clinicians should use some discretion when interpreting the PrEP criteria to ensure that people who are at risk of HIV are not denied access to PrEP if they do not meet the PrEP criteria," he said.
The evaluation of PrEP eligibility criteria was published May 7 in Clinical Infectious Diseases.