09/02/2016 12:35 GMT | Updated 09/02/2017 05:12 GMT

Are We Really More Likely to Die at the Weekend in the NHS?

For several months now, the political fight between NHS junior doctors and the Department of Health has been filling our papers and newsfeeds. The health secretary, Jeremy Hunt proposes to change the contracts of junior doctors in order to have the same junior doctor hospital cover at weekends as on weekdays. However, the doctors say that the contract will force doctors to work even longer and more unsociable hours, which will compromise patient safety. This has led thousands of doctors onto the streets in protest, and the next day of industrial strike action planned for Wednesday 10 February, 2016.

So why is Hunt still not willing to change the proposed contract? The justification given by him and the prime minister is that their aim is to try to fix a serious problem: NHS patients are more likely to die on weekends than on weekdays.

The question is, is this true? Are we really more likely to die at the weekend in the NHS?

There are two main studies that are repeatedly quoted by Hunt and his government colleagues- one looking at overall death rates, and one looking specifically at stroke patients. But is Hunt's analysis of the data valid?

Study 1: Weekend Death Risks

When he initially proposed the contract changes, Hunt stated:

"Around 6,000 people lose their lives every year because we do not have a proper seven-day service in hospitals. You are 15% more likely to die if you are admitted on a Sunday compared to being admitted on a Wednesday."

This referred to a British Medical Journal (BMJ) study which found two relevant sets of results. The authors measured two types of mortality risk:

1. The risk of dying in hospital on a particular day

2. The risk of dying within 30 days of hospital admission, if you are admitted on a particular day

On the first measure of risk, the authors found that there was no significant difference between the risk of dying in hospital on a Wednesday, compared with Saturday or Sunday. To say that your risk of dying in hospital on a Sunday is higher than on a Wednesday is, according to this study, false. There is no difference in risk. In fact, the only significant difference that was found was that the risk of dying in hospital on Friday was slightly higher than on Wednesday. And thus the risk of dying on a Saturday or Sunday in hospital is less than on a Friday!

On the second measure, the study found that the risk of dying 30 days after admission, was significantly higher for admission on Friday, Saturday, Sunday and Monday, compared with Wednesday. The greatest increase in risk was on Sunday admissions. Therefore, to say the risk of dying within 30 days if you are admitted on a Sunday is higher than for a Wednesday is true. However, it also applies to admission on most other days. Therefore, Hunt's quotation is a misrepresentation of the study's findings, as it fails to take into consideration the majority of the study's data.

However, even if we just consider the specific difference between 30-day mortality risk on Sunday compared with Wednesday, the authors of the paper had this conclusion:

"It is not possible to ascertain the extent to which these excess deaths may be preventable; to assume that they are avoidable would be rash and misleading." Compare this with Hunt's quote from above "Around 6,000 people lose their lives every year because we do not have a proper 7-day service in hospitals." Hunt clearly views these excess deaths as avoidable, and so, according to the study's authors, is being "rash and misleading".

Study 2: Dying of a Stroke

The other line repeated by Hunt and Cameron is:

"And at the moment we have an NHS where if you have a stroke at the weekends, you're 20% more likely to die. That can't be acceptable."

This is in reference to a long and complicated study which measured a massive number of variables related to strokes in the UK. The study found that the risk of dying within seven days of having a stroke was 19% higher if hospital admission occurred on the weekend, compared with weekdays. Hunt and Cameron are (more or less) correct with their reading of the data.

However, when it comes to attributing a cause to this mortality-risk increase, discrepancies start to arise. Hunt's contract changes indicate that he attributes this result to decreased Junior Doctor cover over the weekends. However, the study's authors attributed the risk increase to "a higher stroke severity threshold for admission on weekends."

They concluded this because, as well as a 19% increase in mortality risk at weekends, the study also found that the proportion of patients presenting with a stroke who were admitted to hospital was 21% lower at weekends. In other words, only the most severe stroke cases came to hospital at the weekend, while on weekdays hospitals saw both severe and less severe cases.

It isn't really surprising then that a higher proportion of weekend stroke admissions die, compared with weekdays; a higher proportion of weekend stroke admissions are life-threatening, compared with weekdays. The mortality risk increase appears to be nothing to do with junior doctor care of inpatients.

Are We Really More Likely to Die at the Weekend in the NHS?

In 1998, Andrew Wakefield published a study in the Lancet claiming to have found a link between the MMR vaccine and paediatric autism. The data and Wakefield's analysis were quickly found to be invalid and misleading, but before the study could be discredited, the damage had been done. The number of MMR vaccines plummeted and thousands of people have died or become seriously injured from subsequently contracting measles or mumps. One 2011 article even described the Wakefield paper as "perhaps the most damaging medical hoax of the last 100 years"

As both a patient and a medical student observing this junior doctor contract saga roll on, it looks like history is repeating itself. Hunt has repeatedly and unwaveringly misrepresented medical findings, and the results have been deeply concerning. Because of Hunt's misleading public words, anecdotal evidence from doctors says that some patients are now fearful of undergoing medical procedures at the weekend, even if the procedure could be life-saving. The consequences are yet to surface. However, if the Wakefield scandal taught us anything, surely it has shown us how dangerous misrepresenting medical data can be.