What's next for HIV prevention? Paying people to be healthy

Researchers are investigating the impact of offering financial incentives to people who are at risk of acquiring or passing on HIV, the International AIDS Society conference (IAS 2011) in Rome heard last week.

A large study in the United States is looking at whether a test-and-treat approach should be supported by offering incentives to newly diagnosed people who attend medical services and maintain an undetectable viral load.

In sub-Saharan Africa, a number of studies are investigating whether providing incentives to adolescent girls who remain in education reduces their long-term HIV risk.

Such approaches are not without their critics, but those participating in a conference symposium on the topic mostly felt that these interventions are trying to tackle structural factors and have the potential to be effective, especially when used alongside other prevention interventions.

“We shouldn’t look at behavioural economics as the new magic bullet,” commented Professor Quarraisha Abdool Karim of the Centre for the AIDS Programme of Research in South Africa (CAPRISA). “This fits into a broader combination approach,” she said.

As well as cash, incentives may take the form of food or shopping vouchers. They are sometimes called conditional cash transfers, and the approach is sometimes referred to as contingency management.

The idea is already widely used in the development field (often aiming to impact poverty or education), and increasingly in relation to health.

For example, in one study, employees who received cash to complete a smoking cessation programme and to remain smoke-free six and twelve months later had much higher quit rates. People who wanted to lose weight have been more successful when they have had financial incentives, either as a reward or as a lottery prize that can only be won by individuals who have met their weight-loss target.

The conference heard about approaches that provide incentives for people to use preventative health services; incentives for people to remain infection-free; and incentives for pupils to remain in school.

Incentives for testing and follow-up

Dr Mark Hull of the British Columbia Centre for Excellence in HIV/AIDS introduced the concept and particularly its use with substance users. “Contingency management is based on behavioural principles,” he said. “Behaviour is shaped by the environment and any behaviour that is reinforced by a reward usually increases in frequency.”

Incentives have been frequently used to encourage take-up of services by injecting drug users, in response to problems of low coverage and barriers to care.

"...any behaviour that is reinforced by a reward usually increases in frequency.” Dr Mark Hull

Hepatitis B vaccination requires three shots, spread out over six months, and completion rates are often low. San Francisco researchers found that with the use of outreach nurses, a quarter of drug users completed the course, whereas when financial incentives were added, seven out of ten did so. In relation to tuberculosis testing, more injecting drug users have followed up referrals (which require them to travel to another clinic) when cash incentives have been offered.

In the United Kingdom, the National Institute for Health and Clinical Excellence (NICE) recommends the use of incentives in programmes working with drug users. Vouchers can be offered to people who vaccinate against hepatitis B, or to those who test for hepatitis B, hepatitis C, HIV or tuberculosis. When working with people on methadone maintenance treatment, NICE also suggest vouchers or other incentives (such as take-home methadone doses) for clients as long as they test negative for drugs.

Critics say that these kind of programmes are a form of social engineering that pays people to do things that they wouldn’t want to do otherwise. The programmes are paternalistic, dismissing the values and choices of some individuals and imposing the priorities of others.

Supporters counter that the financial incentives help people to achieve outcomes that they desire but might struggle to achieve otherwise – if a drug user didn’t complete the course of vaccinations, was that because he or she would prefer not to do so?

“One thing that many programmes have to overcome in the initial stages is local care provider aversion to these sorts of concepts,” Mark Hull said. Healthcare providers may feel that providing incentives will undermine individuals’ own motivations to live healthily.

Moreover, programmes can be politically controversial, especially when they work with marginalised and stigmatised groups. Some say that they reward ‘bad behaviour’ or are unfair to those individuals who take care of their health anyway but are not eligible to receive payments.

Professor Wafaa El-Sadr of Columbia University is currently leading HPTN 065, a large, multi-component study of different strategies that underpin a test-and-treat prevention strategy. As part of the study, a number of HIV testing sites in New York and Washington DC are offering incentives to individuals who have just tested positive as long as they access an HIV treatment centre within three months of diagnosis.

Payment is made when the first blood tests are done ($25), when the patient attends a first consultation with a doctor ($100) and then for each quarterly viral load test result that is undetectable ($70).

Results are due in 2014 or 2015. As well as reporting on the proportions of people who are linked to care and virally suppressed, the research will also address feasibility and cost.

In response to concerns from healthcare providers and community members, the researchers will collect information on social harms, unintended outcomes and the acceptability of the interventions to the wider community. This was essential to the long-term durability of such projects, Mark Hull suggested.

In Canada, the British Columbia Centre for Excellence in HIV/AIDS is also planning a randomised controlled trial – with HIV-positive drug users – to see whether cash incentives will improve linkage to care and viral suppression rates.

Both these studies are hoping that incentives will encourage people to adhere to medication and keep their viral load undetectable. This appears to be motivated more by the impact on onward transmission than the benefit to the individuals’ own health.

But will it work? While there is evidence for incentives improving uptake of services such as testing or vaccination, Mark Hull warned that the results of a handful of small American studies on incentives for HIV treatment adherence have been less encouraging. While the programmes were running, incentives worked, but they had little long-term impact.

Incentives for staying free of infection

A number of programmes have been developed to work with young people in countries such as Tanzania, Malawi and South Africa. Some have made cash transfers conditional on a person’s sexual health, while others have rewarded school attendance.

At last year’s International AIDS Conference in Vienna, results were reported from the RESPECT trial in Tanzania. This programme randomised young people to a control group or to receive payment every four months if they didn’t have any bacterial sexually transmitted infections (STIs). The researchers considered infection with an STI to be an objective way of measuring risky sexual behaviour that could lead to HIV infection. The testing and treatment of STIs was free to all participants.

Those individuals who were offered $10 every four months when they were STI-free had the same infection rates as the control group, whereas those offered $20 had 25% fewer infections. A participant in the second group could earn $60 in a year, a not insignificant amount when participants’ average annual income was around $250. Indeed, the best results were seen among poorer households and in rural areas.

This study made it clear that the level of incentives offered is vital. Offer too small a reward and it won’t provide enough motivation; offer too much and it may amount to coercion. The right amount is specific to the setting and the group studied.

But can this benefit be sustained over time? A follow-up study, which has now collected its data, should tell us. The incentive programme ran for twelve months, no intervention was provided for a year after that, and then the researchers returned to the study sites to test for STIs once again.

Another programme, this time in rural Malawi, offered an incentive to adults who had the same HIV status one year on. The researchers didn’t see a difference in infection rates between those offered no incentive, an incentive of $4 (around two weeks’ wages) or an incentive of $16 (around two months’ wages).

It is likely that programmes need to be fine-tuned to local economic and cultural conditions. It is possible that these incentives were not large enough to make a difference. Perhaps, as the promised reward was only due a year later, it didn’t have much impact in the here and now.

But a more fundamental question is whether individuals – especially women – really are in a position to act on an incentive by deciding for themselves whether to have sex, who to have sex with and whether to use a condom.

Incentives for staying in school

With these questions in mind, many people believe that incentive programmes need to work with the real determinants of vulnerability to HIV. This has led to the development of a number of programmes which aim to encourage girls to remain in education.

Outside the HIV field, there have been several well-documented programmes that have rewarded school attendance, often in Latin America. A large programme, which provides financial incentives to poor Mexican families to send their children to school and to use health services, has found that the programme increases school enrolment (especially for girls) and has had a long-term impact on various indicators of child development – height, cognition, vocabulary and behavioural problems. The programme has also had a long-term impact on smoking and alcohol use, but not on sexual behaviour.

More generally, economic research in low- and middle-income countries has found that child support grants and pension payments reduce child labour, increase schooling, and improve child health and nutrition.

Commenting on the epidemiology of HIV in South Africa, Dr Audrey Pettifor of the University of North Carolina at Chapel Hill noted firstly that HIV rates in young women are double those in men of the same age.

“And what’s really striking is the rapid increase in infection in a really short period of time,” she added. Whereas 4% of 15-year-old girls have HIV, by the time they reach their early twenties, a quarter to a third are infected.

Moreover, there are striking differences in infection rates according to educational status. For example, women who haven’t completed high school have quadruple the risk of infection, compared to better educated peers. What's more, teenagers who are not in school are more likely to have ever had sex, had sex at a young age, been pregnant, have an older partner or recently had unprotected sex.

Why does attending school make a difference? Pettifor suggested that schooling may have a beneficial effect on self-esteem, self-efficacy and understanding of HIV risks. It may also influence the social and sexual networks that an individual joins – girls in school tend to have sexual partners who are closer to their own age (and so less likely to have HIV).

But barriers to attending school include the costs of school fees, uniforms, books and transport. Moreover, girls are often taken out of school in order to earn money to support the family or to take care of younger children. Can cash transfers that are conditional on attending classes help keep girls in education?

A study in the Zomba district of Malawi – an area where both HIV rates and school drop-out rates are high in adolescent girls – offered financial incentives to households with unmarried schoolgirls aged 13 to 22. Some of the payments were conditional on regular school attendance, while others were unconditional (i.e. regardless of school attendance). The payments included cash transferred to the parents, cash directly to the girl, and direct payment of school fees.

Eighteen months after the programme began, the HIV prevalence among those getting payments was 60% lower than in the control group. Similarly, the prevalence of herpes (HSV-2) was 75% lower.

Importantly, no significant differences were detected between those offered conditional and unconditional payments. This raises the question of whether the programme worked not by incentivising particular behaviours, but by reducing poverty.

“There’s ongoing debate about the role of conditionality as part of these interventions,” commented Professor Charlotte Watts of the London School of Hygiene and Tropical Medicine. “There’s good evidence that conditionality is very important in influencing uptake of services, but I think there’s less evidence at the moment about its impact on rates of partner change or maintaining reduced risk behaviours.”

Girls receiving payments reported fewer sexual partners and fewer sexual acts than other girls, but no more condom use. The researchers believe that the main reason for the lower HIV infection rate was that girls receiving payments had sex with partners closer to their own age and were less likely to have exchanged sex for money. It may be that the additional income made the girls less dependent on using sex as a way to get essential resources.

The intervention was provided for two years (2008 to 2009), and the researchers will return to Zomba in 2012 to collect final data and see whether the health benefit is sustained.

Other important evidence will come from two ongoing trials which are providing cash transfers to rural South African teenagers as long as they attend school.

Quarraisha Abdool Karim is leading a CAPRISA study which has randomised 14 schools to either provide standard life-skills lessons or to provide the lessons plus cash incentives (both to boys and girls). The other trial, led by Audrey Pettifor, is randomising girls either to receive conditional cash transfers or not. In both studies, the primary objective is to reduce the rate of HIV infection. Results are likely to be reported in 2013 and 2015 respectively.

Too narrow a focus?

Speaking from the floor, Professor Ken Mayer of the Fenway Institute wanted the panel to consider other structural interventions, such as law reform around sex work, efforts to tackle homophobia, and training for healthcare workers around linkage to care. Another speaker suggested that one reason these interventions have found favour with a number of governments and donors is that they work at the level of the individual and their impact can be measured in randomised controlled trials. Evaluating the impact of other structural interventions can be more challenging.

Another audience member raised the question of why programmes focused on girls and education. Audrey Pettifor had justified this by the higher HIV incidence in younger women, the stronger links between education and HIV for women, the higher rates of school drop-out in girls and the proven ability of incentive programmes to increase girls' school attendance.

The audience member didn’t question the value of interventions for girls, but said that, in addition, we should be looking at structural interventions for men at the age they are at greatest risk. Describing unemployment as “the most severe structural problem of all in Africa,” he called for randomised controlled trials of interventions that provide employment to young men, with HIV incidence as the primary outcome.

“One of the presumed reasons why helping young women to stay in school might protect them is that it allows them to imagine a more future-oriented perspective on their lives,” he said. Employment could help men in a similar way, he suggested, reducing their likelihood of engaging in self-destructive behaviour.