A mathematical model and cost-effectiveness analysis suggests that annual HIV tests for key populations would prevent nearly as many infections as annual HIV tests for the whole UK population, but at a fraction of the cost.
The analysis includes some unrealistic assumptions – such as current health services being able to achieve 100% coverage of HIV testing – and cannot be read as a simple prediction of future events. But it does indicate the direction we should be aiming for.
At the moment, only around one-in-four gay men and black African people have taken an HIV test in the past year. The model suggested that if this scenario remains unchanged, the number of new HIV infections will not change.
If it were possible to provide HIV testing to all adults (aged 15 to 64) every year, 5% of all future infections would be prevented – due to the impact of HIV treatment on infectiousness. If it’s also assumed that people diagnosed with HIV will have half as many sexual partners as before, then 18% of infections would be prevented.
But the programme would be expensive, costing £80,000 per quality-adjusted life year (QALY) gained. This means that it would cost £80,000 for each extra year that a person lives in good health.
An alternative scenario looked at the impact of annual HIV testing for all members of key populations (men who have sex with men, black African people and people who inject drugs), plus everyone else testing once. This would prevent 4% of future infections, or 15% if diagnosed individuals substantially changed their sexual behaviour.
As far fewer people would need to be tested, costs would be much lower – £17,500 per quality-adjusted life year gained. This is highly cost-effective by UK standards.
HIV Prevention England and National HIV Testing Week aim to increase the frequency with which gay men and black African people test for HIV, rather than trying to achieve this across the whole population. This model provides support for such a targeted approach.