Dr Shipman, who worked as a family doctor in a single-handed practice in Hyde, Greater Manchester, was convicted of 15 murders. But an official UK Government inquiry found that he was responsible for at least 236 deaths over 24 years.
The Papworth Hospital team analysed the Shipman murders and, with the permission of a surgeon and anaesthetist, added in a similar pattern of unexplained virtual deaths to their individual records dating back to April 2000.
They discovered that the hospital's monitoring system would have rung alarm bells at eight months for the surgeon and ten months for the anaesthetist, as the actual death rates would have fallen outside the tolerance zone for predicted death rates.
Papworth is England's main heart and lung transplant centre and its 1,300 staff treat more than 20,000 inpatients and day surgery cases each year, together with 20,000 outpatients.
Both the surgeon and anaesthetist chosen by the authors to take part in the study had been working at the hospital for more than six years. Their performance figures were closest to the average death rates recorded for all staff at the hospital working in their specialty.
The virtual deaths were added into the hospital's point-of-care deaths records, which include details of the patient, operation performed, the outcome and the risk attached to that particular procedure.
Data from these records are analysed once a month by the hospital's clinical audit team and the results from the previous 12 months examined in detail. Annual audits are also carried out on the data, which have been validated by external assessors.
"The system at Papworth wasn't specifically designed to detect serial murders, but to assure that the quality of our surgery service was maintained" explains co-author and consultant surgeon Mr Sam Nashef.
"Papworth has established targets for patient survival after heart surgery, based on patient profiles and the operations performed. It's these targets that would have been breached if the extra virtual deaths had actually occurred.
"There is nothing specific in our study that distinguishes excess death due to malicious intent from any other cause, such as systems failure or human error.
"But it does alert us when death rates fall outside the norm and that is an essential part of any clinical quality assurance programme."
The hospital carried out the study to test the theory - voiced by Professor Mike Harmer of Wales College of Medicine in an editorial in Anaesthesia - that what had happened in a single-handed GP practice couldn't happen in a large and accountable hospital.
This followed the publication of the fifth report of the Shipman Inquiry which looked at how lessons could be learnt and patients safeguarded in the future.
"Some patients would have died during the eight to ten months before the death rates became statistically different from the norm and clinical audit staff were alerted" says consultant anaesthetist Dr Joe Arrowsmith. "But it is sadly inevitable that some harm is done before harm is detected.
"The aim should be to identify and investigate the problem as soon as possible.
"We believe that detailed monitoring of this type is possible in all medical specialities, including general practice, and is preferable to the publication of crude outcome data.
"Universal adoption of robust local monitoring could ensure that terrible events like the Shipman deaths are never repeated."
Dr Harold Shipman was convicted of 15 counts of murder and sentenced to 15 terms of life imprisonment in January 2000 following a lengthy trial. He committed suicide in Wakefield prison in January 2004.
The Shipman Inquiry was established by the UK Government in January 2001 and headed by High Court judge Dame Janet Smith.
Public hearings into individual cases began in June of that year and throughout the life of the inquiry approximately 2,500 witness statements were taken and 270,000 pages of evidence were scanned into the Inquiry database.
Six reports were published between July 2002 and January 2005 and the Shipman Inquiry was decommissioned in Easter 2005.
Controversy over the Shipman murders surfaced again in the media in early May after Inquiry Chair Dame Janet Smith said that the UK Government had so far failed to implement many of her recommendations.
"The work we have done at Papworth demonstrates that we are serious about monitoring the quality of care and have taken steps to ensure that stringent safeguards are in place to protect our patients" stresses Mr Nashef.
Notes to editors
Local clinical quality monitoring for detection of excess operative deaths. Arrowsmith, Powell and Nashef, Papworth Hospital, Cambridge. Anaesthesia. Volume 61, pages 423-426.
Full text versions of all reports from the Shipman Inquiry can be found at www.the-shipman-inquiry.org.uk
Anaesthesia, which was established in 1945, is the official journal of the Association of Anaesthetists of Great Britain and Ireland. It publishes original, peer-reviewed articles to an international audience on all aspects of general and regional anaesthesia, intensive care and pain therapy, including research on equipment. Consultant Anaesthetist Dr David Bogod of Nottingham City Hospital, UK, is Editor in Chief of the journal, which is published by Blackwell Publishing Ltd. www.blackwellpublishing.com/ana
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