Almost 1,000 patients are dying needlessly in hospitals every month due to errors in care.
In research published yesterday, experts estimated there are 11,859 preventable deaths each year in hospitals in England.
The deaths occurred mainly due to poor monitoring of the patient’s condition, wrong diagnosis, or errors in medication or fluid replacement.
Researchers said the figures were substantial but significantly lower than previous estimates which have claimed there are anything from 60,000 to 255,000 cases of serious disability or death each year following NHS treatment.
The analysis of 1,000 adults who died in 2009 in 10 unnamed hospitals in England also found the quality of care three quarters had received was good or excellent.
In the study, doctors looked for potential problems with treatment such as failures to treat or diagnose correctly or incorrect treatment or unintended complications of care.
They found that 5.2 per cent of the deaths had a 50 per cent or greater chance of being preventable – equating to 11,859 deaths in English hospitals each year.
The study, published in the journal BMJ Quality and Safety, found 60 per cent of the preventable deaths occurred in elderly, frail patients with less than a year to live.
Preventable deaths were linked with poor monitoring in almost one in three cases, the wrong diagnosis in another third and poor drug or fluid management in one in five cases.
Lead researcher Helen Hogan, of the London School of Hygiene and Tropical Medicine, said: “While any patient dying from an adverse event is a tragedy and any deaths in hospital due to poor care are of considerable concern, it is important that our estimate of the size and impact of the problem is accurate and we understand what we can do to prevent such incidents.
“Hospitals can and must learn from careful analysis of individual preventable deaths and make every effort to avoid any preventable deaths.”
Concerns about mortality rates at several hospitals in the region have been raised, notably those at the Hull and East Yorkshire Hospitals NHS Trust.
But the authors said the confirmation that a relatively small proportion of deaths appeared preventable offered further evidence that hospital mortality rates “are a poor indicator of quality of care”.
Dr Hogan said that if 95 per cent of deaths in hospital were not due to preventable poor care, “not only is the scope for hospitals to demonstrate reduction in their mortality rate limited, but also the overall mortality rate is not a meaningful indicator of the quality of a hospital”.
The research comes after a coroner this week launched a scathing attack on staff at St George’s Hospital in Tooting, south London, who let a patient die of dehydration in a hospital bed. Staff did not give Kane Gorny vital medication to help him retain fluids. The 22-year-old even phoned police from his hospital bed as he was so desperate for a glass of water.
Deputy Coroner Shirley Radcliffe told the hearing that “a cascade of individual failures has led to an incredibly tragic outcome”.
Last week Coroner Paul Marks ruled teenager Laura Garner’s life could have been saved if staff had carried out basic observations properly.
The 18-year-old, of Baildon, Bradford, died from a serious bacterial infection of the kidney just over 24 hours after she was admitted to Bradford Royal Infirmary.
An inquest was told basic observations including temperature, pulse and blood pressure checks should have been carried out hourly but one gap between them had been 11 hours.
A Department of Health spokeswoman said: “Any preventable death in hospital is unacceptable and we expect the NHS to ensure patients receive high quality, safe and effective care.”