Universal or targeted HIV testing?

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.

PrEP: adherence and resistance

More research suggests that good adherence is key to the effectiveness of pre-exposure prophylaxis (PrEP).

This finding comes from further analysis of the Partners PrEP study, conducted in Kenya and Uganda. Whereas two other PrEP studies conducted with African women had disappointing results due to poor adherence (FEM-PrEP and VOICE), this study conducted with heterosexual men and women showed that PrEP can be effective. All participants in Partners PrEP were in long-term relationships with a partner they knew had HIV – this may have facilitated good adherence.

Over 3000 HIV-negative people took PrEP in the study and 29 of them acquired HIV from their partner. The new analysis examined drug levels in these 29 individuals and in a larger group of participants who remained HIV negative.

Compared to people without detectable drug in their blood, individuals who took their drugs regularly were between 88 and 91% less likely to acquire HIV. (This is a little lower than the estimate from researchers on the iPrEx trial, who believe that people who took four doses a week were 96% less likely to acquire HIV and people who took seven doses a week were 99% less likely to do so).

Most people’s adherence was quite consistent – people who took their pills regularly tended to continue to do so.

One concern about poor adherence to PrEP is drug resistance. In other words, if a person is taking some (but not all) of their prescribed doses of PrEP, becomes HIV positive and continues to take PrEP, could their virus be resistant to tenofovir or FTC? These drugs are used both for PrEP and for treatment of HIV infection.

Reassurance comes from a new analysis of the iPrEx trial – the international study which showed that PrEP can be effective in men who have sex with men.

Two participants had acquired HIV just before they began PrEP, but their acute HIV infections were not recognised at the time. These two men did develop resistance to FTC, but it did not persist after they stopped taking the drug.

Moreover, analysis of blood samples from the 48 men who became HIV positive after beginning PrEP shows that none had resistance mutations or reduced phenotypic susceptibility to the drugs used.

Different PrEP trials conducted with different populations have found adherence to vary significantly. When its results are reported, PROUD, the UK’s study of PrEP, will give us an insight into adherence among UK gay men.

Harm reduction

Taiwanese researchers report that implementation of a comprehensive harm reduction programme has effectively curtailed an HIV epidemic among people who inject drugs. As the UK was one of the first countries to implement such a programme and infections have remained limited here, it’s possible to forget how vital and effective such services are.

In Taiwan, HIV rates had been low in people who inject drugs until an epidemic rapidly emerged in 2004. Within two years the government had implemented a programme of methadone maintenance treatment and needle and syringe supplies, as well as continuing to make HIV treatment freely available.

Analysis of recent HIV infections among people who inject drugs entering prison (who are tested for HIV) shows that incidence has dropped following implementation of the programme. Incidence was estimated to be 6% in 2004, 18% in 2005, 2% in 2007 and 0.3% in 2010.

Researchers also kept in contact with around 2500 prisoners who were released under an amnesty in 2007. All had previously used heroin and were HIV-negative at the time of release.

Incidence in individuals who received methadone maintenance therapy was 0.1%, compared to 1% in those who did not receive it. Incidence in people who frequently used needle and syringe exchanges was 0%, compared to 0.5% in people who did not use those services. It is likely that low viral loads in people taking HIV treatment also contributed to these figures.

Methadone was an integral part of the Taiwanese programme – it is a form of opioid substitution therapy. By helping people reduce or replace their use of heroin, crack and other drugs, fewer injections occur and equipment is shared less often, resulting in fewer HIV infections.

A second study this month compared two forms of opioid substitution therapy – methadone and buprenorphine-naloxone. The latter did have some disadvantages – a higher drop-out rate and an increase in sexual risk taking among males taking it. But most importantly, both methadone and buprenorphine-naloxone were equally effective in reducing the frequency of injecting and the sharing of injecting equipment.

Case study: sexual health screens in a gay sauna

While many organisations offer HIV testing in saunas, a few provide a more comprehensive sexual health screen and some are beginning to offer self-sampling kits to sauna users. One project that is trying out these approaches is run by Mid Cheshire Hospitals NHS Foundation Trust and Body Positive Cheshire & North Wales.

The sauna they work in is close to two motorways and attracts men from across the North West, many of whom are in long-term relationships with women. Around half of those using the service have never had a sexual health screen before but tend to be unwilling to go to a GUM clinic or their GP for this. Moreover, many customers are in their fifties or sixties – the age group in which many men are diagnosed with HIV late (with a low CD4 cell count).

Body Positive have worked in the sauna for several years and put GUM clinicians in touch with the sauna’s management. They worked together to design a service that would suit the specifics of the environment and the customers’ needs. Nurse-led outreach clinics are held every two weeks, offering testing for chlamydia, gonorrhoea, syphilis, hepatitis B, hepatitis C and HIV. Dr Martyn Wood says that a few years ago they couldn’t have offered this range of tests during outreach. It has been made possible by recent improvements in testing methods – nucleic acid amplification tests (NAATs), urine samples and self-swabbing of the throat and rectum.

Clinics are held in a private room near areas used for sex and socialising – the background music prevents discussions with clients from being overheard but the low-level lighting can be challenging. Nurse Moira Grobicki says that the clinics are popular – there is usually a queue and some men come to the sauna especially on the day they take place. Customers appreciate the clinic’s anonymity and convenience. Rather than just take a rapid HIV test, most men prefer to have the full range of tests done and to receive results a few days later, by text, email or phone call.

For customers attending at other times, ‘do it yourself’ self-sampling kits are offered and can be posted back to the GUM. The same range of tests is done, with fingerprick blood samples used for HIV testing. While customers can ask the sauna’s staff for a kit, they seem to be mostly distributed by Body Positive on days when they are doing outreach without the nurses present. There is less demand: for each man returning a self-sampling kit, five see a nurse. It seems that while self-sampling may complement the outreach clinics, it won’t replace them – a personal interaction is needed in this setting.

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