The death rate at 12 NHS hospital trusts in England registered as ‘alarmingly high’ last year, according to an influential report.
The Dr Foster Hospital Guide found that patient safety is also being risked because hospitals are “full to bursting” with many regularly breaching the 85% limit set in place to protect patients.
Figures shows that in 2011-2012 occupancy was running at 88% in midweek, while averaging 90% for 11 of the 12 months, excluding quiet periods including Christmas.
The Guardian, which has seen the report in full, added that the national level was over 85% for 230 of the 365 days of last year, and over 90% for 19.
Dr Andrew Goddard, the director of the medical workforce unit at the Royal College of Physicians, which represents hospital doctors, told the Guardian: “If you ask any doctor in this country they would say that the system is straining to burst; particularly in winter, but now it's increasingly happening the rest of the year.
“Hospitals always seem to be full.”
The report outlines concerns that there could be “another Mid Staffs” as hospitals are increasingly focusing on cost of care rather than quality of care.
Each of the 12 trusts fell short on two of four mortality rate indicators - which include deaths after surgery and the deaths of patients who were admitted for minor ailments or “low-risk conditions”.
“These measures are to be used as a warning sign that poor-quality care may be leading to a higher-than-expected mortality,” the report states.
The authors continue: “With the rising demand for care and falling revenues, there are concerns that trusts will focus more (or exclusively) on cost of care rather than quality of care.
“Because of this, there is a fear that there could be another Mid Staffs.
“Hospital managers must ensure that they do not sacrifice one for the other.”
The report also suggests that a shortage of senior doctors working out of hours could be linked to higher mortality rates at the weekends.
However, University Hospitals Birmingham NHS Foundation Trust (UHB) - one of the 12 trusts named as having higher death rates in two categories - raised concerns about the validity of the Dr Foster indicators.
Dr Dave Rosser, medical director at the trust, said: “The HSMR (Hospital Standardised Mortality Ratio) is widely considered to be unsuitable for use as a comparative indicator between hospitals.
“Dr Foster frequently changes the methodology of the HSMR which, in our opinion, further reduces its credibility as a comparator.”
He continued: “In our opinion, the mortality indicator relating to conditions of low clinical risk is deeply flawed.
“To illustrate, one of the patients identified by Dr Foster to be in this category was a patient admitted into one of UHB's specialist services with a condition called toxic epidermal necrolysis, which is known to have a mortality in excess of 50%.
“Under Dr Foster's methodology, this condition is classified as an allergy and therefore treated as 'low clinical risk'. There are many similar examples.”
The report, which measures mortality indicators at 145 acute hospitals in England, also found that death rates at three hospitals have been consistently high for three years running.
Buckinghamshire Healthcare NHS Trust, The Dudley Group NHS Foundation Trust and George Eliot Hospital Trust in Nuneaton had high mortality rates three years in a row.
Authors of the report alerted authorities to problems at the Mid Staffordshire NHS Foundation Trust - where the deaths rates were also high for a number of years.
At present, Robert Francis QC is finalising details of the report into the public inquiry concerning the serious failings at Mid Staffordshire NHS Foundation Trust.
Kevin McGee, chief executive at George Eliot, said the trust commissioned an external review of its historically high mortality rates last year.
He said: “It is important we acknowledge the HSMR data from the latest Dr Foster Hospital Guide as showing a time when figures were unacceptably high.
“However, we're very keen to focus on the future, where we will aim to maintain consistently low mortality rates coupled with high standards of care.
“We are obviously pleased with the improvements in mortality rates seen so far this year and it is testament to the efforts of all our staff, but we are still some distance from where we want to be.
“We always knew this wasn't going to be a quick fix; this is very much a journey, both for the trust and the wider health economy.”
A spokesman for the Dudley Group said: “We take mortality indicators very seriously and this is one of a number of tools we use to assure ourselves of the quality of our care.
“Current independent analyses show that the trust is not an outlier for mortality. Indeed, recent reports suggest a significant and sustained improvement.”
The Buckinghamshire Healthcare NHS Trust strongly denied that it had a higher than expected mortality rate and questioned whether the hospital guide reflected new ways of operating.
Medical Director Graz Luzzi said: “The title says it all. This is a hospital guide, but our care is also delivered at home, in the community and in a hospice. To be effective it is important to compare like with like.
“Hospice beds are obviously not the same, and the mortality rates between the two will be hugely different. Most hospitals in England don't run hospices, but new integrated acute and community health care trusts do.”
The Trust said the HSMR formula was developed for acute non-specialist trusts only and cannot accurately measure the mortality rate of Buckinghamshire Healthcare since its integration with the community hospitals and hospice.“
:: The 12 hospital trusts where the number of deaths are higher than expected in two of the four mortality indicators are: Aintree University Hospital NHS Foundation Trust, Blackpool Teaching Hospitals NHS Foundation Trust, Buckinghamshire Healthcare NHS Trust, George Eliot Hospital NHS Trust, Hull and East Yorkshire Hospitals NHS Trust, Medway NHS Foundation Trust, North Cumbria University Hospitals NHS Trust, Northern Lincolnshire and Goole Hospitals NHS Foundation Trust, United Lincolnshire Hospitals NHS Trust, University Hospitals Birmingham NHS Foundation Trust, Walsall Healthcare NHS Trust, Western Sussex Hospitals NHS Trust.