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Modelling study – self testing could lead to more HIV infections
Roger Pebody, 2014-01-20 10:00:00

If gay men replace clinic-based HIV testing with less sensitive home tests, the prevalence and incidence of HIV could rise, American researchers report in the January edition of Sexually Transmitted Diseases. Because home tests have longer window periods than laboratory tests, there is a danger that men with recent HIV infection remain undiagnosed, the model suggests.

In 2012, American regulators approved the OraQuick In-Home HIV Test, giving a green light to HIV self-testing at home. In the United Kingdom, legal restrictions on selling such devices will be lifted in April.

systematic review of studies on self-testing has found it to be acceptable across a wide variety of populations, but identified few data on linkage to care after testing positive. One previous modelling study suggested that if inconsistent condom users used self-testing to screen sexual partners, it could lead to fewer instances of unprotected sex and HIV transmission.

The new modelling study was developed on the basis of the sexual and testing behaviour of gay men in Seattle. Of note, men in this setting already test quite frequently – the model assumed that all men test at least once a year, and some more often.

Moreover, broadly in line with trial results of self-tests and data comparing different HIV tests, the researchers assumed that modern clinic-based laboratory tests have a window period of 15 days and detect 100% of infections after this time. In contrast, the OraQuick In-Home HIV Test was assumed to have a window period of three months and to detect 91.7% of infections after this time. While this is the window period stated by the manufacturer, it is quite a conservative assumption (some infections are likely to be detected prior to three months).