Professor Richard Lilford and Dr Yen-Fu Chen of the University's Warwick Medical School, raised the issue following a study that states hospital weekend death risk is common in several developed countries - not just England
Professor Lilford, said: "Understanding this is an extremely important task since it is large, at about 10% in relative risk terms and 0.4% in percentage point terms. This amounts to about 160 additional deaths in a hospital with 40,000 discharges per year.
"But how much of the observed increase results from service failure? And here is the rub, for while a 0.4 percentage point represents a large, potentially scandalous, number of deaths, it is quite a small proportional change".
The experts from the University of Warwick wrote an editorial linked to a paper, The Global Comparators project: international comparison of 30-day in-hospital mortality by day of the week, which was published online in BMJ Quality & Safety.
The authors of the editorial, The ubiquitous weekend effect: moving past proving it exists to clarifying what causes it, believe that there should be more focus on finding the causes behind the 'weekend effect' rather than just proving its existence.
The research found that the heightened risk of death after admission to hospital at the weekend--the so-called 'weekend effect'--is a feature of several developed countries' healthcare systems, and not just a problem for hospitals in England. The international nature of the findings suggests that this is a phenomenon that not only crosses time, but also geography.
The researchers who conducted the study looked at data on almost three million admissions between 2009 and 2012 from 28 metropolitan teaching hospitals in England, Australia, USA and The Netherlands.
They focused on deaths occurring in hospital within 30 days of an emergency admission or elective surgery.
They found that, after taking account of influential factors, the risk of dying within 30 days was higher for emergency admissions at weekends for 22 of the 28 hospitals.
This risk was 8% higher in 11 hospitals in England, 13% higher in five of the US hospitals, and 20% higher in six Dutch hospitals.
There was no daily variation in the heightened risk of death after 30 days for emergency admissions at weekends in the Australian hospitals, and these hospitals between them had the largest proportion of emergency admissions. But those admitted on a Saturday were 12% more likely to die within seven days.
And all patients admitted at the weekend for elective surgery were more likely to die within 30 days across the board than those admitted on other days of the week, the findings showed.
The researchers of the study speculate on the reasons for the findings, pointing out that no one single factor is going to be responsible.
They suggest that certain diagnoses and procedures may be particularly sensitive to reduced access to test results and diagnostics at weekends. Similarly, weekend staff may be fewer in number and less experienced, while patients requiring urgent care may have to wait longer, which might affect the success of any treatment and interventions.
Professor Lilford and Dr Chen were asked to write provide expert comment due to their work on a project to evaluate NHS England's policy drive for seven-day services. Called HiSLAC it examines the intensity of specialist-led care of emergency medical admissions, with a particular focus on weekend provision.
In collaboration with the University of Birmingham they will aim to understand factors likely to impede or enhance the effectiveness of the change in practice.
BMJ Quality & Safety