The advent of pre-exposure prophylaxis (PrEP) use among men who have sex with men (MSM) is associated with declining condom use not only among those taking Truvada (tenofovir disoproxil fumarate/emtricitabine) for HIV prevention but also among HIV-negative men who are not on PrEP, concluded a new Australian study that analyzed reported sexual behaviors among MSM before and after a surge of PrEP use in that nation.
Condom use has been on a two-decade decline among MSM. The advent of effective combination antiretroviral (ARV) treatment for HIV in 1996 ended the crisis era of the AIDS epidemic and thus lowered MSM’s anxieties about condomless sex. More recently, research indicating that HIV-positive individuals who have an undetectable viral load thanks to ARV treatment have effectively no risk of transmitting the virus has also helped relax attitudes toward the risk of HIV transmission through condomless intercourse.
PrEP arrived in this larger historical context, adding yet another biomedical form of protection against HIV into the mix, this one controlled by the HIV-negative person. Truvada was approved for prevention in 2012 in the United States and, following about an 18-month slow start, has become increasingly popular among MSM ever since. Australia, on the other hand, saw relatively minimal use between 2013 and 2016 and then a sudden burst of use in 2017.
A recent study begun in March 2016 in New South Wales, in which researchers rapidly ramped up PrEP use among MSM in the Australian state, found that diagnoses of recently acquired HIV dropped by one third among MSM state residents as a whole after this scale-up. PrEP, they concluded, was likely the driving factor behind the rapid drop in HIV transmissions.
Early studies of PrEP did not show that starting Truvada for prevention was associated with increased sexual risk taking (in the context of highly effective PrEP, the main risk is of contracting sexually transmitted infections, or STIs, rather than HIV), such as decreased condom use. (This is a phenomenon known as risk compensation, akin to applying a high SPF sunblock and spending more time in the sun as a result.) Nor did the studies tend to show that PrEP uptake was linked to an increase in STI rates.
Finally, a recent systematic review of numerous PrEP studies, which were largely conducted in the United States and other wealthy nations, found that starting Truvada for prevention was indeed associated with an increased risk of STIs among MSM. The authors of that paper stated that their findings suggested that starting PrEP was associated with a decrease in condom use, in particular among those already using condoms inconsistently.
The new Australian paper, published in The Lancet HIV, collected data from surveys of 27,011 adult MSM across Australia between January 1, 2013 and March 31, 2017. A total of 16,827 reported sex with casual male partners during the six months prior to being surveyed and were included in the analyses.
The men’s average age was 36 years old. More than 1 in 10 reported recently using crystal meth, and between 15 percent and 18 percent reported recent group sex during or after drug use. Six percent had recently taken post-exposure prophylaxis, and 23 percent had been diagnosed with an STI other than HIV during the previous year.
During the study period, the proportion of HIV-negative men who were tested for the virus during the six months prior to being surveyed increased from 59 percent in 2013 to 77 percent in 2017.
The proportion of HIV-negative men prescribed PrEP during the previous six months was 2 percent in each of the first three years of the study period, 2013, 2014 and 2015; 7 percent in 2016; and 24 percent in 2017.
Among HIV-positive men, the proportion on ARVs at the time of the survey increased from 79 percent in 2013 to 94 percent in 2017 while the proportion with an undetectable viral load at their last lab test rose from 77 percent to 94 percent.
Among all the men, the proportion diagnosed with any STI (other than HIV) during the previous 12 months was 17 percent in 2013, 18 percent in 2014, 20 percent in 2015, 23 percent in 2016 and 31 percent in 2017. The proportion reporting any condomless anal intercourse with regular male partners during the previous six months at each year in the study was a respective 29 percent, 32 percent, 35 percent, 37 percent and 43 percent. The proportion reporting more than 20 male sex partners during the previous six months was a respective 18 percent, 17 percent, 18 percent, 19 percent and 21 percent.
“The large increase in diagnoses of sexually transmitted infection between 2016 and 2017,” the study authors wrote, “is likely to be partially due to the increase in the number of PrEP users in studies, which require quarterly screening for HIV and other sexually transmitted infections.” When men go on PrEP, they typically increase their rate of STI testing as a result. This may lead to a greater rate of STI diagnoses even if men are not actually contracting them more often simply because the infections are more readily detected. Consequently, it can be very difficult for researchers to parse the variables contributing to a higher diagnosis rate.
Among all the participants, measures of their sexual practices during the six months prior to the men being surveyed indicated that the proportion reporting consistent condom use was 46 percent in 2013, 47 percent in 2014, 43 percent in 2015, 42 percent in 2016 and 31 percent in 2017.
Of HIV-negative men who reported condomless anal sex, the proportion who were on PrEP was a respective 1 percent, 1 percent, 1 percent, 5 percent and 16 percent in each year of the study.
Throughout the study period, all HIV-negative men on PrEP who had casual partners reported engaging in condomless anal sex. In other words, no one who took PrEP used condoms consistently.
Out of 14,287 men not on PrEP who were HIV negative or untested for the virus, the proportion reporting consistent condom use declined from 49 percent in 2013 to 40 percent in 2017, while the proportion engaging in condomless anal sex increased from 30 percent to 39 percent during this period
“Our results suggest that jurisdictions should monitor the behavioral effect of PrEP at a community or population level (not only in PrEP users) and uptake modeling to consider community-level risk compensation.”
To read the study abstract, click here.