Non-urgent surgery should be delayed by at least seven weeks after a patient is diagnosed with the coronavirus, research suggests.
Amid the UK's various lockdowns, doctors and officials alike have repeatedly stressed the NHS is open for business.
Before the pandemic hit, studies suggested surgery should be delayed by four weeks after people develop a respiratory infection.
Amid the coronavirus outbreak, international guidelines advise postponing non-urgent surgery in those who have tested positive for the infection, with the recommended length of delay ranging from one to 12 weeks.
Feeling "more granular data are needed", scientists from the University of Birmingham analysed over 140,000 people across 116 countries.
Results suggest going under the knife within six weeks of testing positive for the coronavirus increases an individual's risk of dying within 30 days of the procedure.
Delaying surgery, even if a major operation, was linked to a reduced death risk.
The scientists stressed treatment decisions should be tailored to each patient, with the risks of postponing procedures not always justifiable.
"We found patients operated zero to six weeks after [coronavirus] infection diagnosis are at increased risk of postoperative death, as were patients with ongoing symptoms at the time of surgery," said co-lead author Dr Dmitri Nepogodiev.
"We recommend whenever possible surgery should be delayed for at least seven weeks after a positive [coronavirus] test result, or until symptoms resolve if patients have ongoing symptoms for seven weeks or more after diagnosis."
The Birmingham scientists analysed thousands of patients who had emergency or planned surgery in October 2020 at more than 1,600 hospitals around the world.
Of the patients, one in 50 (2.2%) had been diagnosed with the coronavirus before their operation.
The results reveal 4.1% of those who went under the knife less than two weeks after being diagnosed with the coronavirus died within 30 days of the procedure. The death risk was comparable at three to four weeks, at 3.9%.
It fell slightly at five to six weeks post-diagnosis, at 3.6%.
When surgery was delayed until seven or more weeks later, just 1.5% of the patients died within the next 30 days.
This death rate (1.5%) was also observed among the control participants, who had surgery but never the coronavirus.
The scientists took into account other factors that may raise an individual's surgery-related death risk, like their age, fitness and the disease being treated.
Writing in the journal Anaesthesia, the scientists said: "Therefore, surgery should be delayed for at least seven weeks following [the coronavirus] infection to reduce the risk of postoperative mortality and pulmonary complications."
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The results also show the patients with ongoing coronavirus symptoms were more likely to die following surgery carried out more than seven weeks after their infection diagnosis, compared to those whose illness had resolved or been asymptomatic.
"As such, these patients may benefit from a further delay until their symptoms resolve," wrote the scientists.
Co-lead author Dr Aneel Bhangu added: "Decisions regarding delaying surgery should be tailored for each patient, since the possible advantages of delaying surgery for at least seven weeks following [coronavirus] diagnosis must be balanced against the potential risks of delay."
"For some urgent surgeries, for example for advanced tumours, surgeons and patients may decide the risks of delay are not justified."
The NHS has been open for emergency admissions throughout the pandemic. Many elective operations were cancelled early in the outbreak, however, creating a backlog of tens of millions of procedures.
"Of the millions of patients now waiting for surgery, many will have had COVID-19 [the disease caused by the coronavirus] and they will want to be informed about the risks," said Dr Mike Nathanson, president of the Association of Anaesthetists.
"COVID-19 will be with us for many years and the number of patients with a previous infection will continue to increase."
Yahoo UK has approached NHS England for a comment.
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