Thousands of patients could be dying every year due to the high turnover of nurses and doctors in the NHS, researchers have warned.
More than 4,000 patients in England could be dying annually due to the loss of staff, but this could be a “conservative figure”, they said.
High staff turnover can mean worse care for patients, while a reliance on agency staff to plug gaps in rotas means there is a lack of continuity of care and a lack of expertise, the experts argued.
Published in the British Medical Journal (BMJ), the study, from the University of Surrey and Cambridge University Hospitals Foundation Trust, analysed data for 236,000 nurses, 41,800 senior doctors and 8.1 million patients admitted to 148 NHS acute hospital trusts in England.
It showed that for every 1.21 percentage point increase in the turnover of nurses (around an extra 20 nurses) per month, there were 35 extra deaths per 100,000 hospital admissions within 30 days.
This is equivalent to an extra 239 deaths per month across the 148 hospital trusts.
For senior doctors, a similar increase in turnover rates was linked to an extra 14 deaths per 100,000 admissions, equivalent to an extra 96 deaths per month across the 148 hospital trusts.
Taken together, the researchers said 4,020 extra deaths per year could be happening across the NHS due to the turnover of staff.
The figures were on top of the typical monthly turnover rate of nurses and senior doctors from NHS hospital trusts, which was 2.35% and 2.45% respectively.
Dr Giuseppe Moscelli, associate professor in economics and lead researcher of the study at the University of Surrey, said the loss of life was driven by the care of emergency patients in particular.
He told the PA news agency there are “two big problems” related to staff turnover and how it affects patients.
“First, the NHS works at capacity, meaning we don’t have over-capacity like other systems, like the US, when they usually have more nurses and doctors.
“This means we tend to have shortages of people, of clinical staff, rather than an abundance of people.
“And when too many people leave in a given month or over a sustained period of time, that actually stretches those existing staff that remain.
“The staff to patient ratio goes down…staff have a higher workload and they have less time to dedicate to patients.
“Losing skilled people diminishes the continuity of care and organisational memory within an NHS trust.
“These nurses and doctors have been trained in how things work and so breaking that teamwork with colleagues is detrimental for patient care.”
Dr Moscelli said temporary agency staff can find themselves allocated to different departments regularly, “so they don’t have the time to build all the expertise and the relationship in terms of teamwork to deliver the proper care to patients.”
He added: “Our findings underscore the vital role that stable staffing plays in ensuring patient safety.
“High turnover rates are not simply an administrative issue – they have real, life-or-death implications for patients.”
The data in the study covers the period 2010 to 2019 but Dr Moscelli said he thought 4,020 extra deaths per year was a “conservative estimate” when looking at today’s NHS.
“We know, for example, that shortages of hospital nurses and doctors were detrimental for the survival of Covid patients during the pandemic first wave”, he said.
“The reason why we used data until 2019 is that we needed to cover a stable period in which we didn’t have any other confounding effects, such as Covid created.
“But these are probably conservative estimates compared to what might happen now.”
Dr Moscelli said his message to the Government and NHS England was to find strategies “to retain people, to retain skilled clinicians within the NHS”.
He added: “As our study shows, and as other researchers are also proving with their studies, the turnover is detrimental for patients, and there is a higher chance of burnout of other workers when too many workers leave the NHS.”
The study found high nurse turnover seemed to have a particularly detrimental impact on surgical and general medicine wards, while the loss of senior doctors affected patients suffering infectious and parasitic diseases, mental and behavioural disorders and diseases of the respiratory system the most.
Patricia Marquis, executive director of the Royal College of Nursing, said ministers needed to “take urgent action to keep highly skilled nurses in the profession.”
She added: “Wherever you look, shifts routinely don’t have enough registered nurses to keep patients safe. This has become normalised and is unacceptable.
“Boosting recruitment into the profession is crucial to patient safety, but so too is giving experienced staff a reason to stay.
“Unrelenting pressures, low pay and delivering compromised care are forcing thousands of nurses to quit and it is patients who are paying the price.
“Without safety-critical limits on the number of patients nursing staff are responsible for, patients will continue to be put in danger.
“Nurse-to-patient ratios must be enshrined in law or the cycle that fails everyone will only continue.”
Dr John Dean, clinical vice president of the Royal College of Physicians, said: “This study is a sobering reminder of the human cost of workforce challenge and service pressures.
“It underscores what healthcare professionals have long understood: a stable, well-supported workforce is essential for patient safety.
“Findings from our own census data show that 47% of consultant physicians reported decreased enjoyment in their job over the past year.
“Clinical workload, poorly functioning IT equipment, and staff vacancies in their teams were identified as the top factors negatively affecting their wellbeing.
“Long-term solutions are essential, and the upcoming 10-year health plan and 2025 revision of the NHS long-term workforce plan are critical opportunities to make staff retention and wellbeing a priority.”
The study looked at risk of death from any cause within 30 days of hospital admission, and risk of unplanned readmission within 30 days of discharge after planned hospital treatment.
Assistant director of policy at the Health Foundation, Ruth Thorlby, said the “NHS overall is short of staff and has been for some time”, with almost one in 10 posts vacant last year.
A Department of Health and Social Care spokesperson said: “NHS staff have been overworked for years, leaving them burnt out and demoralised, which is why we accepted the recommendations of the independent pay review bodies to award them with an above inflation pay rise and ended the resident doctor strikes.
“Together with NHS staff and the general public, we will recover and rebuild our health service through the 10 Year Health Plan, making sure the NHS is a great place to work and that patients are getting the right care, where and when they need it.”
