By Michelle Roberts
Health reporter, BBC News
Financial incentive or coercion?
UK doctors are resorting to paying some psychiatric patients in the hope it will make them take their medication.
As a trial, 68 patients with bipolar disorder or schizophrenia will get £15 for every jab of anti-psychotic drug, earning them a possible £720 in a year.
A team at Queen Mary, University of London, hopes to encourage "difficult" patients to comply with treatment.
But Mental health charity Mind said people should be taking medication for the health benefits not for the money.
Non-adherence with medication is a big problem and increases relapse risk and NHS costs.
Experts believe a third of patients with schizophrenia fail to comply with their prescribed medication.
Missing as few as one to 10 days of oral anti-psychotic therapy nearly doubles the risk of a patient being admitted to hospital, they say.
To avoid this, doctors often prescribe depot treatments - injectible versions of the pills - but this is not fail-safe and patients may simply not turn up for their jabs.
Reminder phone calls and texts may fall on deaf ears.
When all other attempts to achieve adherence have failed, bribery may be an option, according to Professor Stefan Priebe, who led the Queen Mary team.
He expects that not only will patients be happy to trade an injection for cash, but that the "money for medication" scheme should pay for itself, with the financial costs more than off-set by the savings made in reduced hospital admissions.
The idea is not entirely new - cash, free public transport passes and even food hampers have been used in Russia to entice TB patients to take their medicine.
And Australian researchers found take-up of child immunisations increased from 6% to 23% when parents were offered a lottery ticket with the potential to win a small cash reward.
In the UK, the National Institute for Health and Clinical Excellence recently published draft guidance on drug addiction, advocating paying drug users to comply with drug cessation programmes.
Professor Priebe's trial includes 136 patients diagnosed with either schizophrenia or bipolar disorder who all have a very poor track record for taking their medication.
Over the 12 months of the study, only half of the patients will be offered the "£15-per-jab" incentive, and all will continue to receive their usual care.
But Professor Priebe recognises the work raises ethical issues.
He said: "We had to seek ethical approval and interviewed 25 focus groups of stake holders. We decided on the £15 sum because it is a relatively small amount of money. It is an incentive.
"You do not want people to become dependent on the money. Also, if we had gone above £20 a week, it would affect people's entitlements to welfare benefits, and many of the patients will be on these."
He has capped the number of "paid" injections at four per month.
Another consideration is whether compliant patients will demand the same money or become poorly adherent in order to be eligible for the scheme.
The mental health charity Mind is worried cash incentives run counter to informed decision-making, coercing patients for pure financial gain.
Spokeswoman Alison Cobb said: "Depot injections are usually given to people with enduring mental health problems who may already be on limited incomes, and the option of being paid to take a drug treatment could unduly influence people's decision-making over whether the treatment is right for them.
"Psychiatric drugs are known to have unpleasant side-effects, and people should take medication because the health benefits outweigh the drawbacks, not because they need the money."