Patients taken to hospitals at weekends are 16 per cent more likely to die than those admitted during the week, a major study suggests.
Researchers found non-emergency operations - such as hip and knee replacements - are 70 per cent more deadly when performed on the weekend compared to a week day.
But experts believe while a 'weekend effect' exists, the higher death rates are not a reflection of poorer care in hospitals on Saturdays and Sundays.
Instead, they claim it is likely the result of patients needing treatment at weekends being sicker and frailer when they are admitted to hospital.
Patients taken to hospitals at weekends are 16 per cent more likely to die than those admitted during the week
Experts say higher deaths at weekends may be due to complications forcing pre-planned operations to be moved forward or pushed back to Saturdays and Sundays.
They believe such errors could slip past an administrative database and add to the increased mortality rate at the weekend.
On the other hand, researchers say elective admissions might be overlooked due to hospitals being configured to care for emergencies at weekends.
The largest-ever review into the 'weekend effect' analysed more than 640million admissions worldwide, including in the NHS.
University of Warwick researchers reviewed 68 studies from 11 countries that looked at weekend mortality rates.
Writing in the British Medical Journal Open, the academics found the weekend effect varied by type of admissions.
Elective admissions - pre-planned hospital visits, usually for operations - were the most fatal at 70 per cent.
Emergency admissions resulted in 11 per cent more deaths at weekends compared with during the week.
And maternity admissions on a Saturday or Sunday had a six per cent increased risk of death, according to the review.
However, the researchers were keen to point out their analysis focused on mixed studies that skewed the average mortality rate.
The 'weekend effect' that is said to make surgery on Saturday or Sunday riskier has been blamed on a lack of skilled senior staff.
Senior doctors – consultants – are