An Essex hospitals trust last night defended its record ahead of the publication of a report naming it as having one of the worst “excess” death rates in the country.

NHS medical director Professor Sir Bruce Keogh has been examining 14 health trusts – including Colchester Hospital University NHS Foundation Trust, which runs Colchester General and Essex County hospitals.

In a report due out tomorrow he is expected to describe poor care, medical errors and management blunders, suggesting that the Stafford hospital scandal was not a one-off. Sir Bruce has been examining 14 hospital trusts that have mortality indexes above what they would expect to see. The trusts in question are braced for tough criticism over thousands of needless deaths.

But bosses at Colchester said last night that it was already taking action to work on its Summary Hospital-level Mortality Indicator (SHMI), one of several ways the NHS measures death rates.

It has acknowledged the SHMI was higher than expected, but assured it was “performing strongly” against other patient safety indicators.

A spokesman for the trust said: “The number of deaths at our hospitals fell by 24.2% (432) between 2005/6 (1,782 deaths in total) and 2012/13 (1,350 in total). The average for all acute non-specialist trusts during the same period was 10.8%.

“Our Hospital Standardised Mortality Ratio (HSMR), which measures only deaths in hospitals, has been within the expected range for several years whereas our SHMI, which includes deaths within 30 days after discharge from hospital as well as in-hospital deaths, is higher than expected.

“We developed a joint mortality action plan with North East Essex Clinical Commissioning Group who have always acknowledged that SHMI is an issue for the whole health system. That is why the Trust and CCG are working with others on this issue, including GPs, out-of-hours services, the ambulance service and St Helena Hospice.

“The trust is performing strongly against other patient safety indicators, such as reducing the number of falls and pressure ulcers, and is scoring well on patient satisfaction.”

David Cameron commissioned Prof Keogh’s report in February after Robert Francis QC’s inquiry into the Stafford scandal exposed appalling lapses in both care of patients and the regulation of hospitals.

Its findings argued for “fundamental change” in the culture of the NHS to make sure patients were put first. It said the trust management ignored patients’ complaints and local GPs and MPs also failed to speak up for them.

A Department of Health spokeswoman said: “We are not prepared to speculate about the contents of Sir Bruce’s review, or our response to it. We’ve shown consistently that we expect the NHS to be accountable where things go wrong.

“That is why the Prime Minister ordered an investigation to get to the bottom of these issues.”