Pre-exposure prophylaxis use to protect against HIV infection was associated with higher infection rates of other sexually transmitted diseases, according to a new study.
An analysis in Australia found more than 2,900 sexually transmitted infections were diagnosed in nearly half of the study's participants from when they started using PrEP. Nearly 3,000 gay and bisexual men were given access to the medication. The study found infections per participant ranged from zero to 12.
The study, published Tuesday in JAMA, found 25% of study participants had multiple infections that accounted for 76% of all infections diagnosed. The incidence of infections increased among participants who already had been tested for STIs.
Researchers found that patients at greater risk of sexually transmitted infections tended to be younger, had used PrEP prior to the trial, and reported having a higher number of anal sex partners and greater participation in group sex compared with those who did not get infected.
The study did not find a significant increase in risk based on the frequency with which patients used condoms, indicating that there was not a clear association between consistent condom use and decreased risk of infection.
Condom use has historically been strongly associated with decreasing the risk of STIs. But the study found no significant difference between those who reported using condoms more than half of the time they had sex, compared with those who used them less than half of the time, all of the time, or never using them at all during sex with casual partners. Researchers deduced that could stem from study participants' low consistent condom use.
"Findings suggested that STI prevention campaigns should not focus solely on condom use but also on reducing the time to STI diagnosis and treatment by promoting easy access to frequent testing," the study concluded.
In an accompanying editorial, Drs. Monica Gandhi and Matthew Spinelli, both from the University of California at San Francisco's medicine department, and Dr. Kenneth Mayer of the Fenway Institute in Boston, cautioned that the study's results should be viewed in context with, and not outside of, current trends among gay and bisexual men—increases in sexually transmitted infections that have been occurring within that group even prior to the availability of PrEP in 2012.
The writers also stressed the importance of condom use. They said evidence has shown concerns among clinicians about whether patients who take PrEP would begin to engage in riskier behavior has led some not to offer the medication. A 2018 report in the journal Clinical Infectious Diseases found increasing rates of sexually transmitted infections among PrEP users who were engaging in unprotected sex.
Many experts see increasing the use of PrEP among high-risk individuals as one of the key factors toward achieving the Trump administration's pledged goal of reducing new HIV infections by 90% by 2030.
PrEP was first approved in 2012 to prevent HIV transmission and has an efficacy rate of about 97% when taken consistently. But use has been relatively low among the population that it could benefit most. Of the estimated 1.1 million Americans identified in 2015 as possibly benefiting from taking PrEP, only 90,000 prescriptions were filled that year, according to the Centers for Disease Control and Prevention.
Encouraging greater use of PrEP was what prompted the U.S. Preventive Services Task Force last year to recommend clinicians offer PrEP to patients at high risk for contracting HIV.
"To continue to achieve the population-level influence on HIV incidence through PrEP that appears imminently achievable, PrEP will need to be available for and used by the populations that can benefit the most, including those having condomless sex," the commentary stated.
