Patients are more likely to die if they endure long waits in A&E before being admitted to a hospital bed, according to new research.

The study, published in the Emergency Medicine Journal, found waiting longer than five hours in A&E increased the risk of dying from any cause within 30 days, with the risks going up the longer people waited.

Medics working in NHS departments said the issue has got worse since the study was carried out, while one lay member of a royal college said the four-hour A&E target, which is due to be scrapped, is of “key importance to patient safety”.

The new study examined data from more than five million patients in England who were admitted to major A&E departments between April 2016 and March 2018.

The results showed that waiting longer than five hours in A&E increased the risk of dying. The “greatest change” was an 8% increase among those patients who waited in emergency departments more than six to eight hours before being admitted.

For every 82 admitted patients who waited more than six to eight hours for a bed, there is one extra death, the researchers said.

The data further indicates a 10% increased risk of death for patients stuck in A&E for between eight and 12 hours in comparison with those who leave within six hours.

NHS England data from earlier this month showed that a record 12,986 people had to wait more than 12 hours in A&E departments in England in December from a decision to admit to actually being admitted.

The figure is up from 10,646 in November and is the highest for any calendar month since records began in August 2010.

Some 120,218 people waited at least four hours from the decision to admit to admission, slightly below the all-time high of 121,251 in October.

The current measure requires 95% of A&E patients to be seen within four hours, but has not been met for many years and is set to be axed.

For the new study, researchers, including from NHS England and Improvement, the Royal Bolton Hospital, University of Exeter Business School and Musgrove Park Hospital in Taunton, concluded that the extra deaths are caused by delays to hospital admission from A&E departments rather than crowding alone.

They looked at deaths compared with what would normally be expected when taking into account sex, age, deprivation, existing health issues, previous A&E attendances and crowding in the department at the time of the attendance.

Among 5,249,891 admitted patients, some 433,962 deaths occurred within 30 days.

The researchers noted that the most frequent time of arrival was between noon and 6pm, with the first three months of the year accounting for the biggest proportion of patients.

Patients admitted between April and December had a lower death rate than those admitted between January and March, the study also found.

The authors said that “exit block” – when not enough beds are available to move people onto wards – can delay access to vital treatments.

They added: “This study confirms that healthcare policy makers should continue to mandate timely admission from the [emergency department] in order to protect patients from hospital-associated harm.”

In an editorial, Derek Prentice, lay member for the Royal College of Emergency Medicine, said: “Let nobody be in doubt any longer, the NHS four-hour operational target is, as many of us have always known, of key importance to patient safety.”

Dr Katherine Henderson, president of the Royal College Emergency Medicine, said in a statement: “We welcome this paper, which adds to the evidence of what we have long warned – that long waiting times present a serious threat to patient safety.

“Performance in emergency departments has been in decline for many years now, while waiting times have risen significantly.

“The risk to patient safety is a growing problem. It is unacceptable and deeply concerning. No patient should be kept waiting to be admitted to a bed.

“As the paper mentions, long delays are usually caused by ‘exit block’ – where patients cannot move onto the next stage of their care due to capacity problems outside of the emergency department.

“We must eliminate this and is consequent practice, corridor care, urgently.

“To do this will require long term resourcing – the Government must commit to publishing a long-term workforce plan for the health service and take effective steps to address the ongoing social care crisis.

“The study also confirms that policy makers should continue to mandate timely admission from the emergency department to protect patients from hospital associated harm.”

Dr Simon Walsh, deputy chair of the consultants’ committee at the British Medical Association (BMA), said: “This study used data from before the pandemic started and, sadly, we know that more patients are now waiting much longer than the target of four hours, with a huge increase in the number who are waiting over 12 hours to be seen and admitted.

“This exit block from emergency departments, caused by a lack of any spare capacity in hospitals, also leads to delayed ambulance handovers, sometimes for several hours, with devastating effects on ambulance response times also resulting in harm to patients.

“The reason that patients are having to wait longer for emergency ambulances and emergency treatment in hospital is because of decades of underinvestment in the NHS, combined with a workforce crisis.

“It’s clear that hospitals simply do not have the capacity to cope; patients who are medically fit for discharge remain stuck in hospital while awaiting social care which means that there is no capacity to admit emergency patients in a timely manner, which ultimately leads to unacceptable delays in emergency departments and ambulance services.”

An NHS spokesperson said: “Pressure on NHS emergency departments is high, with more than 26 million attendances recorded between 2016 and 2018 when this research took place, and in spite of the additional challenges as a result of the pandemic, NHS staff are working incredibly hard to respond to rising demand and provide expert care for as many patients as possible.

“NHS England is supporting trusts to better understand their individual demand and capacity and reduce long waiting times in A&Es, and last autumn set out a 10-point action plan to support hospitals with significant demand this winter and beyond.”