Californians seemingly have more unprotected sex after starting on HIV preventative drugs.
Some men report having more sex without condoms after starting on a daily pill to prevent HIV, according to an unpublished survey of 90 patients from one California healthcare provider.
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The result doesn't represent all users of the drug, Truvada, and it doesn't prove that taking the drug leads men to have riskier sex, researchers said. The result also stands in contrast to two rigorous peer-reviewed trials of the drug.
The doctor who conducted the survey said the finding is leading to a formal study.
"We need more information to really clarify the information we do have," said Dr. Jonathan Volk, who helped conduct the survey at Kaiser Permanente in San Francisco.
May reduce risk by 92 percent
Truvada, which is manufactured by Gilead, is approved in the U.S. for pre-exposure prophylaxis or PrEP. The pill may reduce the risk of HIV infection, which leads to Aids, by as much as 92 percent, according to the U.S. Centres for Disease Control and Prevention.
As of right now, Volk said the survey shows the drug is working to prevent HIV.
"We now have over 500 patients on this medication and we have zero new infections," he said.
The CDC advises people taking Truvada to continue using condoms, because the pill does not completely protect against HIV and does not protect against other sexually transmitted infections, which are effectively prevented through condom use.
Volk told Reuters Health by phone that he decided to survey around 100 of his patients who had been taking Truvada for about six months to get a better understanding about their behaviours and experiences with the drug. The results have not been peer-reviewed for publication in a journal.
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The vast majority of the patients are men who have sex with men, Volk said.
Of 90 men who responded to the survey, 45 percent reported decreased condom use since starting on the drug.
"We can't say that PreP is causing people to make that decision," Volk said.
He added that there is a lot they don't know about the men who responded to the survey. For example, they don't know how many are in committed, monogamous relationships. They also don't know to what degree condom use decreased.
Not compared to non-drug users
The researchers didn't compare the respondents to another group of men who don't take the drug, so they can't tell if condom use is declining among non-Truvada users, too.
For example, if men stop wearing condoms when they're in a committed relationship with one person, a comparison group not using PreP might show a similar decline in condom use among some men.
Alternatively, Volk said it could be that people's condom use would change over time and decrease anyway.
"We can't really determine that without the control group," he said.
Condom use would decrease anyway
Volk said it could be that they're reaching exactly the right people at the right time, because their condom use would decrease anyway.
"These are important clinical questions that we need to look at and plan to formally, but not from the data we have now," he said.
The survey results contrast with a 2013 randomized clinical trial – considered the highest quality medical evidence – among approximately 2 500 men and transsexual women in six countries.
Although participants did not know whether they were getting Truvada or a dummy pill, rates of HIV and syphilis infection fell, suggesting a decrease in risky behaviour.
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Volk said he received a grant from Kaiser Permanente to study Truvada users. The study will look at adherence, outcomes and side effects.
As of right now, he said, "The major point is that this drug was approved for preventing HIV and if anything our experience supports that this medication is working."