Annual HIV tests for high-risk groups and one-off screening for all others could have a big impact on UK's HIV epidemic

Michael Carter
Published: 09 May 2014

The UK’s HIV epidemic could be partially curtailed by annual testing of high-risk groups and one-off screening for other populations, investigators report in PLOS ONE. The authors calculated this strategy would prevent between 4 and 15% of future HIV infections and would be highly cost-effective. Their estimates assumed current levels of antiretroviral use.

“Targeted HIV testing of specific key populations is cost-effective in the UK,” comment the researchers. “This finding is potentially relevant to other low-prevalence, high-income countries.”

According to the most recent estimates, 98,000 people are living with HIV in the UK. Around a quarter of these individuals are unaware of their status.

The UK epidemic is concentrated in three key populations: gay and other men who have sex with men (MSM); people who inject drugs; and black African people.

Guidelines recommend annual HIV tests for gay men and other individuals who may be at higher risk. Universal screening is also recommended in settings where local HIV prevalence exceeds 0.2%.

Research conducted in the US and France suggests that certain “test and treat” strategies can cost-effectively prevent a substantial number of new HIV infections.

A team of UK and US investigators therefore developed a model to estimate how many new HIV infections would be prevented by specific screening strategies and also how affordable these strategies would be.

They estimated the impact of testing strategies on HIV incidence and quality-adjusted life years (QALYS) – an important measure of cost-effectiveness. HIV testing and counselling was assumed to cost £44 per person, but the extra costs of achieving universal HIV testing coverage were not incorporated.

If current HIV testing and treatment levels remained unchanged, then HIV incidence would remain more or less steady with approximately 3500 new infections each year. More than 6100 people would be newly diagnosed with HIV in 2013, and 5400 of these would involve people from high-risk groups.

If it were possible to provide HIV testing to all adults (aged 15 to 64) every three years, 1% of all future infections would be prevented, while universal testing every year would prevent 5% of future infections. These reductions in incidence would be a consequence of the impact of antiretroviral treatment on infectiousness. If diagnosis with HIV were accompanied by a 50% reduction in number of sexual partners, then between 3 to 18% of future infections would be averted. Annual universal testing would diagnose 16,000 infections in the first year, substantially reducing the number of individuals living with undiagnosed HIV infection.

However, cost-effectiveness was a major limitation of this strategy.

In the modest optimistic scenario (50% reduction in the number of sexual partners), annual HIV testing for all adults would cost £64,000 per QALY gained. With no behaviour change, the cost was over £100,000 per QALY gained. It would take approximately 11,000 tests to identify one person with HIV.

A testing programme targeted at high-risk groups that was combined with one-off screening for other adults prevented nearly as many infections as universal screening, but at a much lower cost.

In this scenario, 100% of MSM, people who inject drugs and black African people would test every year and other people would take an HIV test once.

This strategy would prevent between 4 and 15% of future infections. There would be 15,000 new HIV diagnoses in the first year – almost as many as would be achieved with universal testing.

Targeted testing with one-off screening for other adults was projected to cost £17,500 per QALY gained. A total of 2500 tests would be required to identify an individual with undiagnosed HIV infection.

Linking expanded uptake of antiretroviral therapy with targeted testing and one-off screening for other adults was shown to prevent up to 23% of future infections at a cost of £26,800 per QALY gained. This strategy would remain cost-effective with 100% uptake of HIV therapy.

The investigators therefore conclude a targeted testing approach with one-off testing for others, would provide 80% of the benefits of universal HIV testing but at only 14% of the cost over ten years. “At £17,500/QALY gained, this strategy is well below established UK cost-effectiveness thresholds of £20,000-£30,000/QALY gained.”

Reference

Long EF et al. Expanded HIV testing in low prevalence, high-income countries: a cost-effectiveness analysis for the United Kingdom. PLOS ONE 9(4): e95735, 2014.