AN investigation has been launched into high death rates in the intensive care unit of Aberdeen Royal Infirmary.

The external review is the latest in a series of probes examining care at the hospital - with one damning report flagging up serious shortages of doctors and nurses as well as a forceful style of management.

However, NHS Grampian, which oversees the hospital, said they believed a "data entry issue" had contributed to the mortality figures for the ICU and said the unit offered "first class specialist care".

The alert was raised by the Scottish Intensive Care Society Audit Group (SICSAG) who look at death rates and other performance measures to help drive up standards in Scotland's critical care units.

Dr Stephen Cole, chair of SICSAG and an intensive care consultant, said the mortality figures for Aberdeen could be higher than expected due to chance alone. However, he added: "I would personally want to reassure the public that ARI take this very seriously and they are stunned by this and they want to explore the reasons why this might be the case."

The SICSAG report for 2015 also revealed Glasgow Royal Infirmary intensive care unit had the lowest death rate in Scotland while Edinburgh Royal Infirmary ICU had to discharge almost one in ten patients early last year because of bed and staffing shortages.

Dr Cole said: "I think you could conclude from the data that critical care capacity in Edinburgh Royal Infirmary is under stress, but other units have made improvements."

Health Secretary Shona Robison said the report showed that, despite a significant increase in admissions, "more people are surviving critical illness than ever before as a result of the quality of treatment they receive in intensive care."

She added: “We are aware that this report has picked up a higher mortality rate at Aberdeen Royal Infirmary compared to the rest of Scotland. Of course, the reasons behind a higher mortality rate can be extremely complex – particularly in units where patients come in in an already critically ill condition. That is why the Scottish Intensive Care Society will be carrying out an external review to investigate the reasons behind this higher mortality rate and better understand why this occurring.”

NHS Grampian said: “We have examined our audit process and believe there is a data entry issue which has contributed to these figures. We are working to resolve that error to ensure that these figures more accurately reflect patient data in the intensive care unit in the future.

“We are also aware that there are often other complex underlying factors which may influence these figures and so in order that we can provide assurance to patients, relatives and staff, we have also commissioned a further external review of the data and the unit which will report shortly."