Scores of deaths at a hospital may have been wrongly attributed to septicaemia, a report has found.
An independent report into the "coding" of 150 cases at the Royal Bolton Hospital found more than half did not "meet national standards". Coding is an NHS technical process for the classification of conditions and is used by medics in treatment and analysis.
Wednesday's interim report, by health watchdog Dr Foster, was commissioned by the Bolton NHS Foundation Trust following the discovery that an "unusually high number" of deaths were coded as due to septicaemia. The Trust's acting chief executive, Dr Jackie Bene, stepped aside last week pending the inquiry.
Septicaemia, a severe infection which enters the bloodstream, is coded in a different way from other illnesses and infections, which means deaths caused by septicaemia do not affect hospital mortality figures. Dr Bene, as former medical director, was in charge of recording the information.
The trust said the watchdog probe found that of 150 patient cases - not all fatal - coded as septicaemia and reviewed by Dr Foster, 76 were found not to meet national coding standards. Of these, 69 were as a consequence of the retrospective clinical validation process, the hospital added.
Responding to the report, Dr Wirin Bhatiani, chair of Bolton Clinical Commissioning Group, said: "The final report confirms that clinical coding of sepsis is of concern. This report looked at the quality of the coding process; we now need medical input to understand how and why this happened, and to understand if the coding was clinically appropriate.
"We have no evidence clinical care of patients has been compromised. We have jointly agreed with Bolton NHS Foundation Trust the scope of an independent, clinically-led review and the terms of reference with its chair David Wakefield."
The hospital recorded 800 cases of septicaemia between March 2011 and April 2012 - a similar sized trust would expect to have just 200. A more in-depth review has now been ordered by the Clinical Commissioning Group (CCG), which is replacing the primary care trust, and is expected to focus more closely on fatal cases.
A CCG spokesman said: "As a result of the report's findings and recommendations, we are now supporting a further clinical review to understand the implications of Dr Foster's findings from a clinical perspective. The independent clinical review team will be chaired by Kathy Doran, an experienced chief executive, and be clinically led by Dr Peter Williams, who is an experienced consultant physician to offer an independent clinical perspective."
In its response to the report, the Royal Bolton Hospital said it was "important to note that the report raises no concerns about standards of treatment and care". Bolton NHS Foundation Trust chairman David Wakefield said: "We are pleased that the report raises no concerns about standards of treatment and care. We want to ensure that trust's coding validation process meets the highest quality standards and have agreed with the CCG the remit of an independent clinical review."