Statistical methods usually employed as industrial quality-control measures might have allowed authorities to catch mass-murdering UK doctor Harold Shipman much earlier than he was, according to a new study. The method, which can also be used to uncover awful surgeons or poorly-performing hospitals, is now being tested in pilot schemes by the UK's Healthcare Commission, an independent body which monitors public health services. Harold Shipman - the UK's most prolific serial killer - was convicted in 2000 for murdering 15 of his patients as a GP or community doctor. But it is believed that he may have murdered a further 245, between 1975 and 1998. His victims were mostly elderly female patients, to whom he administered fatal doses of morphine. Shipman hung himself in his prison cell in January 2004. Now David Spiegelhalter of the UK Medical Research Council's Biostatistics Unit, Cambridge, UK, has applied an industrial quality-control technique to data on the death of Shipman's patients to see if his heinous crimes could have been detected any earlier. The method was first used in 1943 to ensure consistent quality in explosive shells and other wartime munitions production lines, says Spiegelhalter. The same statistics are used today in a wide range of industries, but have never before been applied to healthcare performance. "Maths has many crime-fighting applications," comments applied mathematician Chris Budd at the University of Bath, UK. "Statistics can be a useful approach for detecting anomalies in many contexts," he says.
Monitoring the excess death among Shipman's patients may not have been enough alone to detect the murders, says Spiegelhalter. Some other general practitioners – those who regularly work in care homes or hospices for example – have been shown, understandably, to have a higher patient fatality rate. But cross-referencing other factors such as time of death or location might have set alarm bells ringing – many of Shipman's victims were murdered at around 3pm, during his afternoon rounds, and anomalous numbers died while in Shipman’s presence.