A key measure of hospital death rates should be ignored, according to the expert leading the review into them.
Academic Prof Nick Black has been asked by the NHS to see whether they are an accurate indicator of poor care.
His review is not due to be published until December, but he told the BBC the most established method of measuring mortality appeared to have no value.
But Dr Foster – the research group which has pioneered their use – rejected the criticism.
Prof Black’s team are looking at two measures of mortality – the hospital standardised mortality ratio (HSMR), which compares the expected rate of death in a hospital with the actual rate of death, and the summary hospital-level mortality index (SHMI), which covers deaths after hospital treatment and up to 30 days after discharge.
Prof Black has already looked into HSMRs, but is now doing this in more detail as well as looking at SHMIs.
He told BBC Radio 4’s File on 4 programme that based on what he already knew, HSMRs should be ignored.
He said they could not entirely take into account factors such as burden of illness and were skewed by other factors such as the availability of hospice care in the area – where there is less hospice care patients are more likely to be in hospital when they die.
“I don’t think there’s any value in the publication of HSMR and I’d go further, I think it’s actually a distraction because it gives… a misleading idea of the quality of care of a hospital.”
When asked what the public should make of media coverage of death rates, he added: “Personally, I would suggest that the public ignore them.”
Prof Black was asked to look into mortality rates after a review by Prof Sir Bruce Keogh, published in July, found failings in care at the 14 hospitals with the highest death rates.
Despite the findings, Sir Bruce said he was not sure how accurate an indicator death rates were.
This comes amid a growing desire to use them to identify hospitals at risk of providing poor care.
The Care Quality Commission is now using them alongside other factors to decide which hospitals to visit first under its new inspection regime.
Supporters of mortality data maintain they are not a confirmation of poor care, but rather should be seen as a “smoke alarm” in that they highlight a problem that needs investigating.
Roger Taylor, of Dr Foster, said there were countless examples where death rates had identified problems, including in the Stafford Hospital scandal.
“What they do is they identify those areas where there’s a greater risk of poor quality care,” he added.