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Gay men who were offered HIV home-testing kits took 50% more tests than men who only took HIV tests at clinics or community organisations, a randomised controlled study from Seattle in the USA has found.

The men who could self-test took fewer tests for sexually transmitted infections (STIs), though it is not completely clear whether this was because they went less often for STI checkups or had fewer STI symptoms. Provision of self-testing made no difference to sexual risk behaviour.

The study was not powered to detect whether self-testing made a difference to HIV incidence, but four out of six men who tested HIV positive during the study were in the self-testing arm. None of these infections were diagnosed with a self-test. Three of the four men took a self-test no more than two months before being diagnosed.

The study was conducted from 2010 to 2014 and initially reported at the IAS conference in Vancouver in 2015 – this report mentions the results.

The study was conducted among 230 gay men and men who have sex with men in Seattle. The men met the study’s criteria for high risk of HIV during the previous year, which were: condomless anal sex with HIV-positive or unknown-status partners; ten or more male sex partners (condomless or not); a diagnosis of a bacterial STI; or methamphetamine or poppers use.

Half the men were provided with self-test kits and half were asked to carry on testing as normal at STI clinics, community organisations, and with private physicians.

Men in the self-test arm were only allowed one self-test kit per month. This was done both to allow more accurate documenting of test use, and also to try to ensure participants did not give the test kits to friends to use (this actually happened several times, with one person testing positive). It's interesting to speculate whether home-testing rates might have been even higher if re-testing did not sometimes involve a trip to the clinic.

During the study in 2012, the OraQuick HIV self-test became publicly available (it had only been used in research before), but this appeared to make no difference to testing frequency.

The average age of study subjects was 36.5 and 75% were white (with 18% of those being classed as Hispanic), 9.5% African American, and 5% Asian. Fifty-five per cent had education to degree level. Thirteen people in the study (5.5%) were homeless.

Most people (92.5%) had tested for HIV in the last year – 2.25 times on average. The mean number of sexual partners in the last three months at baseline was 5.25, but condomless anal sex had only happened with one of them on average. Only a third of participants had had condomless anal sex in the last three months with an HIV-positive or unknown-status partner. About 10% had used methamphetamine and a third poppers in the last three months.

There were a couple of slight differences between the study arms. More people in the clinic-testing arm has actually used a home test in the past (ten vs two individuals), and more of them had had STIs diagnosed (chlamydia and syphilis) in the last year (19% vs 8%). These differences were not significant though.

Men randomised to self-testing took 49% more HIV tests during the 15 months of the study than men in the control arm – 5.3 tests (one every 2.8 months) vs 3.6 tests (one every 4.1 months). This averages out as an increase of 1.7 tests over the 15 months. Over 75% of men in the self-testing arm took a test at least once every three months as recommended, vs 54% in the control arm.

The men randomised to receive self-test kits could also take clinic tests; in fact 49% did, with 41% only taking self-tests, and 10% rejecting self-testing and opting for clinic testing only. Of the 5.3 tests taken by men in the self-test arm, 1.4 were actually at a clinic. But they still took more self-tests than the total number of clinic tests by men in the control arm.

When only tests that could be independently verified were included, there was a bigger difference between the arms with self-testers reporting 4.7 verifiable tests in 15 months and control-arm testers 2.5, an 88% difference.

Men in the self-test arm took fewer tests for STIs, however: 2.3 during the 15 months compared with 3.2 in the control arm.

It makes sense that because self-testers did not have to come to a clinic for HIV tests, they took fewer STI tests. Interestingly, however, fewer self-testers than men in the control arm were diagnosed with an STI in a screen at the end of the study: 5.4% vs 12.2%. That was not quite statistically significant, but raises the possibility that men in the self-test arm could have taken fewer STI tests because they experienced fewer symptoms.

There was no difference in HIV risk. Although men in the self-testing arm were slightly more likely to report non-concordant condomless anal sex, they reported slightly fewer sex partners, and no differences were statistically significant.

The men reported that they expected they would test more often if they had access to self-tests; the median amount they would be willing to pay for a test kit was $10 to $20. Twelve per cent said they would only use self-tests if they were free.

Six men (3.4%) tested HIV positive during the study, four in the self-testing arm (not a significant difference). This equates to an annual incidence of 2.75%, compared with 0.4% among the general clinic-using Seattle gay population.

All four positive men in the self-test arm had used a self-test within two months of diagnosis. One tested positive at a test he took at a clinic because his partner had just tested positive. He took a self-test, which was also positive, between taking his clinic test and receiving its result.

In the other three cases, none had their first positive result via a home test. One had taken a negative home test two months prior to the end of the study – where the test he took, at his last clinic visit, was positive. In the other two cases, they took clinic tests because they had symptoms suggesting acute HIV infection – in one case only five days after his last negative self-test, and in the other a month after.

The researchers comment that their study shows that HIV testing frequency can be pushed up even further among a high-risk population that already tests quite often. However, they acknowledge that it remains to be seen whether providing HIV home-tests will encourage increased testing among people who test much less frequently, or not at all, as least in the high-income gay population. Self-testing provision has produced considerable increases in the frequency of testing in some studies in Africa.

The researchers are also concerned that self-testing could produce adverse results in terms of HIV infections if the tests are not sensitive enough or their ‘window period’ too long, and they therefore give people a false sense of security. Concerns about this has resulted in fingerprick blood tests being preferred to oral-fluid tests in recent self-test provision.

The researchers also note that since then, pre-exposure prophylaxis (PrEP) has arrived, and that the oral-fluid test used in the study may not be sensitive enough or provide results soon enough after infection for people to self-screen for HIV before starting PrEP.

Katz DA et al. HIV self-testing increases HIV testing frequency in high-risk men who have sex with men: a randomized controlled trial. JAIDS 78(5): p 505-513. August 2018. See abstract here.