The new organ donation system in England is “unlikely” to increase the number of donations, researchers have claimed.

The comments come after a new study found that under opt-out systems, families felt the wishes of their loved ones were more ambiguous compared to opt-in systems.

The new system for England, which will come into effect in 2020, will mean people, apart from certain groups, will be considered organ donors unless they have explicitly recorded a wish not to be.

A new study, conducted by experts at Queen Mary University of London, examined people’s thoughts on organ donation in various countries which had both opt-in and opt-out organ donation systems.

Many organ donor systems across the world include a clause which allows the final decision to donate to be made by family members.

And families vetoing organ donation is said to be one of the biggest barriers to donation.

Indeed, the authors highlight figures from NHS Blood and Transplant which show that in 2010, 500 families vetoed organ donations despite being informed that their relative was on the NHS Organ Donor Register. This led to an estimated 1,200 people missing out on potentially life-saving transplants, they wrote.

In England there have been specific drives encouraging people to tell their loved ones about their wishes surrounding organ donation in the event of their death.

The study, published in Journal of Experimental Psychology: Applied, included more than 1,200 American and European participants from countries that had either opt-in or default opt-out systems to take on the role of a third party to judge the likelihood that an individual’s “true wish” was to actually donate their organs, given that they were registered to donate on the organ donation register.

Participants were presented with a fictional scenario about a person involved in a fatal accident which left their vital organs intact.

They found that people perceived the donor’s underlying preference to donate as stronger under the opt-in or mandated choice systems.

“We found that ambiguous signals of underlying preference that are attached to default opt-out systems contribute to families’ veto decisions compared to active choice systems (opt-in, mandated-choice) which are substantially better at signalling intent than passive ones,” they wrote.

They added: “When participants know that an individual has registered their decision to donate through some overt signal (i.e. under a mandated choice or a default opt-in system) this is likely perceived as a less ambiguous signal of a preference to donate.”

Lead author Dr Magda Osman, from Queen Mary University of London, said: “We show it’s harder to judge the underlying wishes of the deceased if they were on an opt-out and mandatory donation register.”

Dr Yiling Lin added: “There are plans to launch an opt-out organ donation system in England, but what we show is that this system is unlikely to increase actual rates of organ donation or reduce veto rates, all it will do is increase the number of people on the organ donation register.”

Officials hope the new system of consent for organ and tissue donation in England could save hundreds of lives.

People who do not wish to donate their organs will still be able to record their decision on the NHS Organ Donor Register, either via NHS Blood and Transplant’s website or by calling their helpline.

Commenting on the new study, an NHS Blood and Transplant spokesman said: “This is a decision for the Government and Parliament. We believe that the new legislation will encourage more families to talk about organ donation and this will support an increase in donation.

“We know that currently around eight out of 10 people support organ donation but only around a third of people have told their families that they want to donate.

“Our research work, based on projections and on evidence from Wales and the EU, estimates a change to an opt out system could result in an average of 100 extra donors a year in England. The number could be higher and we also expect there may be increases in Wales and Scotland.

“Under the new legislation, you would still be able to express a decision to opt into donation, and you would still be able to opt out. People who do not register a decision will be deemed to have given consent for donation.”

Health Minister Jackie Doyle-Price said: “Organ donation saves lives. We believe that by making these changes, we will save and transform hundreds of lives every year.

“But organ donation remains a gift. I want to encourage people who wish to give life in the event of their death to take the time to record their wishes and discuss it with their family.

“However, we know this new system alone will not break down every barrier. We need to address myths and misconceptions around donation, and we will only do this by having informed debate and dialogue, which will be fostered by these proposals.”