Men with HIV and men on PrEP in Boston see large increase in sexually transmitted infections

Douglas Krakower at IDWeek 2016. Photo by Liz Highleyman,
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Rates of gonorrhoea, syphilis and chlamydia have risen steeply at Fenway Health in Boston since 2011, according to a presentation last week at IDWeek in New Orleans. Being HIV-positive men and using pre-exposure prophylaxis (PrEP) to prevent HIV were associated with higher risk of getting sexually transmitted infections (STIs), but more frequent STI testing and treatment could potentially help reduce the numbers.

Studies of gay and bisexual men have shown that tenofovir/emtricitabine (Truvada) PrEP reduces the likelihood of HIV infection by more than 90% if used consistently. A common concern is that PrEP will lead people to stop using condoms, putting them at risk for other STIs. This "risk compensation" was not seen in clinical trials that led to approval of Truvada for HIV prevention, but it has been reported in some PrEP demonstration projects and real-world use.

PrEP trial participants and clients of PrEP programmes generally do have high rates of STIs, but this is true at the outset before they start taking Truvada. Most studies indicate that men at highest risk for HIV – which includes those who already do not use condoms – are most likely to seek PrEP. And in many cities STI rates were on the rise well before PrEP became widely available.



A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.


Chlamydia is a common sexually transmitted infection, caused by bacteria called Chlamydia trachomatis. Women can get chlamydia in the cervix, rectum, or throat. Men can get chlamydia in the urethra (inside the penis), rectum, or throat. Chlamydia is treated with antibiotics.


In the United States, a programme providing health insurance to people on low-incomes of all ages. Provision varies from state to state, although some types of care are covered in all states.

multivariate analysis

An extension of multivariable analysis that is used to model two or more outcomes at the same time.

demonstration project

A project that tests and measures the effect of a treatment or prevention approach in a ‘real world’ setting. Usually done after clinical trials have shown that the intervention is efficacious, but while there are outstanding questions about how it can be best implemented.

Douglas Krakower of Beth Israel Deaconess Medical Center and colleagues used electronic health records to analyse trends in PrEP use and STI rates at Fenway Health, which specialises in the care of sexual and gender minorities.

A total of 19,238 men visited the clinic at least once between 2005 and 2015. About three quarters were white, 6% were black, and 10% were Latino. While 43% identified as gay and 3% as bisexual, just over half did not report a sexual orientation. With regard to healthcare coverage, 62% had private health insurance, 5% each were on Medicaid (for low-income people) and Medicare (for seniors), and 8% reported no insurance.

About 15% of Fenway clients were HIV-positive. While the number of people with newly diagnosed HIV infection has fallen in Massachusetts overall, it is rising at Fenway Health, suggesting consolidation of HIV care at this centre. In 2004, 6% of all HIV diagnoses in the state were made at Fenway Health, rising to 14% in 2013.

From 2004 to 2014, the median CD4 cell count at the time of antiretroviral therapy (ART) initiation rose, from 238 to 464 cells/mm3, as did the proportion of people starting ART within a year of HIV diagnosis (from 68% to 97%) and the percentage achieving viral suppression (from 57% to 86%).

Among HIV-negative clients, the rise in PrEP use in over the past five years has been "very rapid and steep," according to Krakower. The number of Fenway clients receiving prescriptions for tenofovir/emtricitabine for PrEP rose from just five in 2011 to 960 in 2015. Last year 14% of all men seen at the clinic for any reason ended up with a PrEP prescription.

Between 2005 and 2015, 18% of men seen at the clinic were diagnosed with at least one bacterial STI: 7% with gonorrhoea (3% rectal and 4% urogenital), 7% with syphilis and 9% with chlamydia. Almost all cases occurred among men who have sex with men. By 2015, 14% of HIV-positive people and 25% of HIV-negative PrEP clients had at least one STI. But Krakower stressed that it is "hard to infer causality" from this type of data, and noted that a substantial number of men who were HIV-negative and not on PrEP got STIs as well.

Rates of all three bacterial STIs rose over time. Syphilis increased over the entire period between 2000 and 2015, with an accelerated rise starting around 2011. Gonorrhoea was relatively stable from 2003 to 2010, then shot up dramatically in 2011 – a "near astronomical rise," Krakower said. Chlamydia was only reported since 2011, showing a steady, steep increase since then. Taken together, the combined number of bacterial STIs at Fenway rose from 162 in 2005 to 1329 in 2015.

Being HIV-positive and using PrEP were both independently associated with a greater likelihood of being diagnosed with STIs in a multivariate analysis (hazard ratio 2.66 and 3.43, respectively). Being African American or of mixed race, and being on Medicaid, uninsured, or without stable health insurance were also associated with a higher STI risk, but these associations were not as strong.

"This work really emphasizes the need to educate people when they are receiving PrEP about the risk of acquiring sexually transmitted infections," said Pablo Tebas of the University of Pennsylvania at an IDWeek press briefing previewing highlights of the meeting.

While rising STI rates among gay and bi men are a concern, the regular clinic visits recommended for HIV-negative people on PrEP may offer more opportunities for frequent STI testing and prompt treatment.

The US Centers for Disease Control and Prevention PrEP guidelines recommend STI tests at least every six months, but indicate that some people may benefit from testing more often.

Researchers with the PrEP Demo Project, which enrolled at-risk gay men and transgender women in San Francisco, Miami and Washington, DC, recently reported that 40% of chlamydia, 34% of gonorrhoea and 20% of syphilis cases would have been missed if STI screening had been done every six instead of every three months.

"There probably is a big population – even at a place like Fenway where clinicians and patients are quite attuned to issues around sexual health and PrEP – who may benefit from some more intensive screening and counselling around PrEP, as they're not yet using it," Krakower suggested.


Mayer K et al. (Krakower D presenting) HIV Infection and PrEP use are independently associated with increasing diagnoses of bacterial sexually transmitted infections (BSTI) in men accessing care at a Boston community health center (CHC): 2005-2015. IDWeek, New Orleans, abstract 2379, 2016.