Does paying drug users boost hep B jab uptake?

"Heroin addicts are being 'bribed' with £30 in shopping vouchers for agreeing to undergo vaccinations," The Daily Telegraph reports, while the Daily Mail said addicts were to get a "£10 supermarket 'bribe' to stay clear of drugs and £30 to have a hepatitis B jab".

Some of the reporting makes it sound as if drug users will soon be awash with NHS cash. In fact, there are two studies being covered here – one of which is completed and published, and a second that is ongoing.

The published study involved just over 200 injecting drug users being treated for heroin addiction. The researchers wanted to see if a small cash incentive of supermarket vouchers given in instalments up to £30 would increase the likelihood of drug users completing a course of vaccinations against hepatitis B.

Hepatitis B is a blood-borne virus that can be caught from sharing needles, as well as from unprotected sex. It is estimated that one in five injecting drug users has the disease.

The offer of vouchers led to dramatic results in some, but not all, participants. Drug users given the supermarket vouchers were at least 12 times more likely to complete a course of hepatitis B injections than those who were not given vouchers. However, half of the people offered an incentive did not complete the course.

While people may baulk at the idea of "bribing" drug users to get vaccinated, the proposal could save the NHS a great deal of money in the long run. A report from the Foundation for Liver Research (PDF, 734kb) estimated that treating hepatitis B costs the NHS up to around £375 million a year.

Where did the story come from?

The study was carried out by researchers from Imperial College London, King's College London, University College London, South London and Maudsley NHS Foundation Trust, Camden and Islington NHS Foundation Trust, Central and North West London NHS Foundation Trust, and Sussex NHS Foundation Trust. It was funded by the National Institute for Health Research.

The study was published in the peer-reviewed medical journal, The Lancet. It has been published on an open access basis and is free to read online.

Coverage of both studies was somewhat shrill, with The Independent referring to a "controversial trial" offering cash to drug addicts, while the Daily Mail and The Daily Telegraph referred to a voucher "bribe". The Mail also misleadingly implied that the £30 voucher is currently offered to those who had a hepatitis B jab, but this was only as part of a study.

There is room for debate over how NHS resources are best used. But this debate should also include an estimate of the savings that might be made in terms of future care and treatment if offering financial incentives means fewer drug or ex-drug users get hepatitis B.

The societal cost of heroin addiction is also estimated to be large. Aside from the actual cost of treating addicts, there are also additional costs associated with the crimes many addicts engage in to pay for their habit. If a £10 shopping voucher stops your house being burgled, you may consider that a price worth paying.

What kind of research was this?

This research was a cluster randomised trial involving 210 people receiving treatment for drug addiction. It aimed to find out if giving small financial incentives could improve the number of people that completed a vaccination schedule against hepatitis B. A cluster randomised trial is where groups of people (as opposed to individuals) are randomised.

The researchers point out that in general, poor adherence to treatment is a widespread problem that reduces the individual and public benefit from numerous health interventions. This problem is especially acute among heroin users, who often lead chaotic lives.

They say that interest in a strategy known as contingency management, which involves the use of material or financial incentives to promote adherence to treatment, is gaining ground. The National Institute for Health and Care Excellence (NICE) supports its use in some circumstances.

The researchers also point out that injecting drug users are a major risk group for infection and transmission of hepatitis B, with 22% of this group being affected. Clinical guidance recommends that routine hepatitis B vaccination is offered to people receiving addiction treatment, but uptake of the vaccine needs to be improved.

They aimed to assess the effectiveness of cash incentives in promoting the completion of hepatitis B vaccination among those receiving treatment for addiction, compared with the offer of vaccination without such an incentive.

What did the research involve?

Participants for the trial were all undergoing opioid substitution therapy for drug addiction at 12 NHS drug treatment clinics in the UK. All the clinics offered an accelerated hepatitis B vaccination schedule as advised in clinical guidelines, providing three injections on days 0, 7 and 21 of treatment.

Adults aged 18-65 years were eligible if they had previous, current or future risk of injecting drug use and were eligible for hepatitis B vaccination (they had not previously received a vaccination or had hepatitis B infection).

The clinics the drug users attended were randomly allocated to provide three different approaches:

• hepatitis B vaccination without any cash incentive (treatment-as-usual group)
• hepatitis B vaccination with a "fixed-value" incentive – participants received up to £30, provided as a £10 voucher at each of the three vaccinations
• hepatitis B vaccination with an incentive that increased in value – where participants received up to £30 in vouchers, provided as a £5 voucher at the first vaccination visit, a £10 voucher at the second vaccination visit, and a £15 voucher at the third vaccination visit

In the second and third groups, eligibility to receive a voucher was conditional on attendance at the appointment on time and compliance with the vaccination schedule.

Patients completed a research interview before enrolment into the trial, which assessed their socioeconomic background, drug and alcohol use, drug treatment history, and health.

Patients were given a first vaccination appointment (day 0) at least 24 hours after enrolment. Attendance at the three hepatitis B vaccination appointments was recorded for up to three months.

Researchers primarily looked at completion of hepatitis B vaccination within 28 days of the first vaccination day.

Patients were defined as completers if they attended all scheduled vaccination appointments, or attended but were not vaccinated because they were found to have existing immunity.

They also recorded incidence of any serious adverse events, assessing if these were related to vaccination.

Standard statistical methods were used to analyse the results.

What were the basic results?

These are the main findings:

• 9% of participants treated as usual (with no incentives) completed the vaccination schedule
• 45% of participants who received three £10 vouchers completed the vaccination schedule (odds ratio [OR] 12.1, 95% confidence interval [CI] 3.7-39.9)
• 49% of participants who received vouchers of increasing value completed the vaccination schedule (OR 14.0, 95% CI 4.2-46.2)
• no serious adverse events related to treatment occurred

How did the researchers interpret the results?

The researchers say their findings are in accord with previous studies. They say their results provide compelling evidence that financial incentives significantly improve completion of the three-injection vaccination schedule, so that approximately half of patients complete vaccinations as scheduled.

Further work is now required to improve on this method and thereby increase the number of drug users who complete the vaccination schedules.

"That monetary incentives increase compliance is unremarkable, but the size of the increase we observed was striking," says Professor John Strang from the National Addiction Centre at King's College London, who led the study.

Strang goes on to say that, "Injecting drug users are at high risk of infection and transmission of hepatitis B. This is a potentially life-saving vaccine, and increasing its uptake among this group has important benefits to public health, as well as to the individual."

Conclusion

This was a well-designed study which found that a small cash incentive offered to drug users receiving treatment increases the likelihood that they completed a course of injections to protect them against hepatitis B.

However, it should be noted that about half the patients receiving cash incentives did not complete the vaccinations. As the authors point out, more research is needed to improve on the method.

It should also be noted that this trial involved patients already receiving treatment for drug addiction. These patients are more likely to be motivated to receive vaccinations than injecting drug users who have not gone into treatment.

A further limitation to the strength of the results is the wide confidence intervals, which may have been the result of a reasonably small sample size.