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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.
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).