Will patients really die this week because of new NHS hospital doctors?

Will patients really die this week because of new NHS hospital doctors?:

Today is "black Wednesday", day one of the killing season, when hospital death rates spike by 6%. But is it really true? Help us find the facts
• Data journalism from the Datablog
August 1 is the day when thousands of new doctors begin work in NHS hospitals around the country or move to new jobs. If you believe today's Telegraph, this is "Black Wednesday", the start of the "killing season".

Studies have shown that patients admitted as an emergency on the first Wednesday in August are six per cent more likely to die than on the previous Wednesday

The Daily Mail has also reported this apparent increase in death rates, with a report entitled "'Killing season' on NHS wards: Patients at risk when junior doctors start new jobs"

Hospital death rates go up by 8 per cent when junior doctors start their jobs in what a top NHS executive has labelled a 'killing season'

It quotes Sir Bruce Keogh, medical director of the health service

The intention is to end the so-called killing season. This is good news for patients – we recognise the change-over period in August puts patients at risk

But is it true? Full Fact have carried out an excellent analysis of death rates in hospitals and this guide to the Black Wednesday theory.
There are two different numbers to deal with, just to start: the Telegraph's 6% and the Mail's 8%. Full Fact points out that the original research is a 2009 Imperial College study, Early In-Hospital Mortality following Trainee Doctors' First Day at Work.
This study looked at 175 hospital's mortality rates by day between 2000 and 2008. For reach year, the researchers compared emergency admissions on the last Wednesday in July and the first Wednesday of August, "black Wednesday".
Full Fact reports:

Overall, the researchers found that once factors such as age, gender and socio-economic deprivation had been taken into account, there was a six percent increase in death rates for the first Wednesday in August compared to the previous Wednesday between 2000 and 2008

So, the Daily Mail's 8% is down to it taking a larger figure in the report which factored out patients with cancer and those undertaking surgery. So it's right, but the variables are important.
The report itself says (and I recommend going to the original):

The odds of death for patients admitted on the first Wednesday in August was 6% higher after controlling for year, gender, age, socio-economic deprivation and co-morbidity. When subdivided into medical, surgical and neoplasm admissions, medical admissions admitted on the first Wednesday in August had an 8% higher odds of death

The study found that typically, there are actually less patients going to A&E on the first Wednesday in August than the week earlier. They also found that the most common diagnoses associated with death for the first week of August were: pneumonia, lung cancer and heart attacks.
It also compared the system before and after the junior docotrs' applications system changed in 2008.

In 2007 and 2008, when the system for junior doctors' job applications changed, patients admitted on Wednesday August 1st had 8% higher adjusted odds of death than those admitted the previous Wednesday, but this was not statistically significant

But does the rise mean that hospitals are somehow more dangerous?
The report author Dr Paul Aylin points out that

Our study does not mean that people should avoid going into hospital that week. This is a relatively small difference in mortality rates, and the numbers of excess deaths are very low

We'd like to pull your expertise and knowledge into this story. Is the report right - and what does it really tell us about "black Wednesday"? The Guardian