Baby deaths ‘30 times higher’ under Lucy Letby’s care
Baby deaths ‘30 times higher’ under Lucy Letby’s care
Statisticians dispute chief medical expert’s deduction, claiming more data needed for accurate analysis
Sarah KnaptonScience Editor
Babies were thirty times more likely to die under the care of Lucy Letby, the chief medical expert in her trial has claimed, in new figures disputed by statisticians.
The data were compiled by Dr Dewi Evans, who said he had only recently received a copy of Letby’s shift patterns and could not carry out the calculations earlier.
Since Letby was convicted, statisticians have come forward to warn that a shift pattern chart shown to the jury – which placed the nurse at every death and collapse – was flawed because it did not include other instances where she was not present.
Dr Evans, a retired paediatrician from Carmarthen, said he believed statistics “played no role in the prosecution case” but said he had gone over the shift data and found that 9.2 per cent of Letby’s shifts involved a death or collapse compared to 0.3 per cent for other staff.
He told The Telegraph: “I’ve frequently stressed that statistics played no role in the prosecution case against Letby.
“But the statisticians keep insisting that the famous spreadsheet was flawed as it did not include information regarding the other deaths during 2015 and 2016.
“In simple terms, infant mortality was over thirty times greater when Letby was on duty compared to when she was not.”
Dr Evans said he had found that there were 15 deaths during Letby’s 163 shifts, compared to two deaths during the 635 shifts when she was not on duty.
However, statisticians said the calculations missed some crucial data.
Peter Elston, an independent statistician, said to make an accurate comparison, an expert would need to know information such as how many nurses were on duty per shift and what were the differences in competencies between the nurses.
“It may seem like these numbers are significant, (but) in order to carry out a robust and accurate statistical analysis, we would need to take into account a variety of other factors,” he said.
Data crucial for more robust analysis
Jane Hutton, a professor of statistics at Warwick University, also said more data would be needed for an accurate analysis.
Prof Hutton was originally engaged by Cheshire Police and asked to put a figure on how likely it would be for one member of staff to be on duty for all deaths and collapses.
She told officers that a proper statistical inquiry must look into all possible explanations for the babies collapsing, including their medical conditions and prematurity, and the performance of the unit. The prosecution later told police not to pursue that line of inquiry.
Speaking of the new analysis by Dr Evans, Prof Hutton said: “One also needs to know how many babies were on the neonatal intensive care unit, and the severity of illness of each infant, multiplicity (twins/triplets) etc.
“Without confirmation of the data on shifts, particularly times of day, as well as the relevant information about the severity of illness of the infants, this calculation is meaningless.”
Prof Hutton has also written to the Thirlwall Inquiry – which is investigating how deaths at the Countess of Chester Hospital could have been prevented – complaining about their use of statistics and offering to assist them with data.
In September, Richard Baker KC said an audit had shown that the dislodgement of breathing tubes occurred at a rate 40 times higher than normal during Letby’s shifts when she worked at Liverpool Women’s Hospital in 2012 and 2015.
At the time, experts wrote to Lady Justice Thirlwall warning that the claims were “not credible”.
In a new letter to Mr Baker, Prof Hutton said she was writing to express concern at the “very poor presentation of statistics”.
She added: “I might be able to assist you. I am concerned that without professional statistical advice, you might misinform the public when you present further information on this to the Thirlwall Inquiry.
“I know, of course, that the prosecution instructed Cheshire Constabulary not to inquire into the validity of statistical evidence.
“Deaths of babies are tragic. Incorrect statistics are no remedy.”
Letby was convicted of killing seven babies and attempting to murder seven more at the Countess of Chester Hospital between 2016 and 2017.
This week, she was voluntarily questioned by the police over more deaths and collapses that allegedly happened at the Countess and when she worked as a student nurse at Liverpool Women’s Hospital in 2012 and 2015.
Mark McDonald, Letby’s barrister, told The Telegraph that he had more than 50 experts lined up to defend the nurse and said that she maintained her innocence. Mr McDonald is planning to take her case to the Criminal Cases Review Commission (CCRC).
Dr Evans has said he will not enter the witness box in any future trials.
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