Mortality risk for patients in hospital is higher at the weekend the during the week, research showsReuters

Patients are more likely to die in hospital if they are admitted over the weekend, according to a new global study.

The work by Japanese researchers pooled the results of studies that included 55 million patients in 72 countries. It is the most comprehensive study yet undertaken to examine the relationship between when people are admitted to hospital and how likely they are to die.

A second study of more than 200,000 patients undergoing operations in Germany between 2006 and 2011 shows the chance of dying in hospital was higher in the afternoon than in the morning, higher at weekends and higher in February.

Both studies, presented at a European conference on anaesthesia in Stockholm this weekend, support the findings of previous research into patients in intensive care units.

Last year, a study in the BMJ found the risks of surgery became progressively higher from Monday to Saturday. It found that patients who had an operation on Friday or Saturday were more likely to die within 30 days than those who had surgery on a Monday.

But relatively few operations are carried out at weekends in NHS hospitals. Fewer than 5% of all elective operations – pre-booked non-emergency procedures – are done at the weekend, NHS England figures show.

Researchers say that people who do have operations at weekend may be sicker, or more likely to be having riskier procedures than people who are operated on during the week. They say this is more likely to explain the higher risk associated with weekends than poorer quality care.

In the UK ministers have already acknowledged that hospital care suffers at the weekends, and plans are in train to ensure more doctors and senior doctors are available at weekends.