"NHS death rate is one of worst in the West," says the Daily Mail, while The Times front page warns of "Alarm over 'high' death rate in English hospitals".

This story was covered by most UK news outlets, including The Daily Telegraph, which reports that NHS patients are 45% more likely to die than patients in the US. The Telegraph says that data "over more than 10 years found NHS mortality rates were among the worst of those in seven developed countries".

The media report on previously unpublished data given to Channel 4 News by the statistician Professor Sir Brian Jarman (see About Professor Brian Jarman). Channel 4 News revealed the findings in an evening news bulletin on September 11.

The news is shocking and attention-grabbing, but as Professor Jarman points out, his work is not proof of a particular problem with the NHS. Instead, he says it is "no more than a trigger to further see whether the large differences in adjusted death rates … indicate possible differences in the quality of hospital care in the two countries".

The NHS is looking into what the data shows and what can be done to address the issues raised.

How did Prof Jarman work out that death rates were higher in England?

Channel 4 News reports that for the for the past 10 years Professor Jarman has been collecting data and developing an index called the hospital standardised mortality ratio (HSMR). The current data comes from England, the US and five other unnamed countries with advanced economies.

HSMRs look at whether actual death rates in hospital are higher or lower than would be expected, taking into account patients' age and severity of illness. If death rates are as expected, the hospital scores a HSMR of 100. If mortality is lower than expected, they score less than 100, and if higher than expected, they score more than 100.

Professor Jarman tells Channel 4 that he was "quite frankly shocked" at the findings, and for years he looked for a flaw in his methodology.

The only data publically available is a brief publication comparing US and English HSMRs, where Professor Jarman also raises potential flaws or caveats about the data. Data for England appears to have been retrieved from the Hospital Episode Statistics (HES), which collects details of all NHS inpatient treatment, outpatient appointments and A&E attendances in England.

However, no further methodology has been provided for England or other countries, so we can't say whether the methods used to collect data on HSMRs over the past 10 years were appropriate. Professor Jarman's analysis does not appear to have been peer-reviewed.

What does Prof Jarman's comparison show?

From both Professor Jarman's discussion with Channel 4 News and his published figures, the key points are:

Almost 10 years ago, in 2004, there were 22.5% more deaths in English NHS hospitals than would have been expected, giving England the highest hospital death rate of the seven countries examined.

HSMRs in the NHS were 58% higher than the best country, the US.

Since 2004 things have improved, but in 2012 a patient in the average NHS hospital was still 45% more likely to die in hospital than if they had been admitted to a US hospital.

People over the age of 65 fare worse. Elderly people are five times more likely to die of pneumonia in hospital in England and twice as likely to die from a blood infection (septicaemia) than if they were admitted to a hospital in the US.

Comparing the number of hospitals in England and the US that had HSMRs in the different ranges, the majority of US hospitals tended to fall into the less than 100 bracket, meaning their hospital death rates were lower than expected.

The majority of English hospitals tended to fall into the 100 to 150 bracket, meaning their death rates were slightly higher than expected – that is, if they had the average mortality rate for all the hospitals in the countries examined.

The average HSMR for England was 122.4, making it the highest of the seven countries examined. The average HSMR for the US was 77.4.

Professor Jarman also looked at deaths from common individual disease causes, including:

heart attack

heart failure

stroke

pneumonia

fractured neck of femur

He found that HSMRs in the UK have been showing a general downwards trend over the past 10 years. The decreasing rate is faster in England than in most other countries, including the US.

Prof Jarman's data has been used to create graph showing these compartive trends in mortality between English and US hospitals.

What could be the cause of the differences in mortality rates in England?

Professor Jarman said that people should take notice of the data because it gives a "hard measure" of differences in adjusted death rates between countries.

Of course, England's health service is different from that of the US, but survival is the key outcome that matters most to people, he told Channel 4 News.

Professor Jarman notes in his report that compared with several of the other countries examined, England has:

poorer cancer survival

longer waiting lists

lower patient input, with only a small proportion of hospital complaints formally investigated

lower GP out-of-hours on-call service

lower rates of services, including lower use of diagnostic procedures such as MRI, heart surgery, and lower immunisation rates

a lower number of doctors per bed and per 1,000 population

a lower number of acute beds per 1,000 population

Channel 4 News highlights potential criticisms of comparisons between US and NHS hospitals. For example, in the US more money is spent on equipment, drugs and staffing levels because of an "expensive, much-criticised insurance-based healthcare system".

However, Channel 4 cites the example of the Mayo Clinic Hospital in Arizona, which it says exemplifies a system where many safety systems are in place, with checking and re-checking of outcomes and "whistleblowing" when things go wrong. It is a place where, they say, "the patient comes first".

However, as Professor Jarman highlights, the amount of money spent doesn't necessarily mean the best outcomes. He reports that the US spends more than twice as much per person on healthcare as the UK and still has lower life expectancy and higher infant mortality rates.

Around a third of the US population – often the poorest – have no or inadequate healthcare insurance, and so are probably less likely to be covered or go to hospital. Professor Jarman says that if admitted to hospital, these people could be left with a bill they can't pay, which would be a disincentive for poorer people to be admitted.

Therefore, it's worth noting that the mortality rates presented in the data reflect death rates in hospitals and not among people who die outside hospital. It is possible that the poorer groups in society could fare equally well in the NHS, or even better, than they would do in the US.

Further, the differences in the way healthcare systems are paid for in the US can potentially have an influence on the way episodes of healthcare are recorded.

It should also be noted that high HSMRs should not automatically be taken as an indicator that all hospital care is poor.

What will the NHS do to address higher hospital mortality rates?

Professor Sir Bruce Keogh, medical director of the NHS, told Channel 4 News that the new data will be taken seriously.

He says that he wants the English medical system to be based on evidence and such data should not be disregarded simply because it is inconvenient or embarrassing.

The data should be used to improve the NHS, he says. Professor Keogh goes on to say that he will "be the first to bring this data to the attention of clinical leaders in this country".

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Analysis by Bazian

Edited by NHS Website