Seven weeks appears to be the ideal amount of time to delay surgery, when possible, after someone tests positive for COVID-19, researchers in the United Kingdom report.
Risk for death was about 3.5 to 4 times higher in the first 6 weeks after surgery among more than 3,000 people with a preoperative COVID-19 diagnosis compared with patients without COVID-19. After 7 weeks, the 30-day mortality rate dropped to a baseline level.
The study was published online March 9 in Anaesthesia.
Surgery should be further delayed for people who remain symptomatic at 7 weeks post diagnosis, lead author Dmitri Nepogodiev, MBChB, said in an interview.
“In this group we recommend waiting until COVID-19 symptoms resolve, if possible. However, our study did not capture specific data on long COVID … so we are unable to make specific recommendations for this group,” said Dr. Nepogodiev, research fellow at the NIHR Global Health Research Unit on Global Surgery at the University of Birmingham (England).
“This should be an area for future research,” he added.
The international, multicenter, prospective cohort study is notable for its sheer size – more than 15,000 investigators reported outcomes for 140,231 surgical patients from 1,674 hospitals across 116 countries. In total, 2.2% of these patients tested positive for SARS-CoV-2 prior to surgery.
Surgery of any type performed in October 2020 was assessed. A greater proportion of patients with a preoperative COVID-19 diagnosis had emergency surgery, 44%, compared with 30% of people who never had a COVID-19 diagnosis.
Most patients were asymptomatic at the time of surgery, either because they never experienced COVID-19 symptoms or their symptoms resolved. The 30-day mortality rate was the primary outcome.
Death rates among surgical patients with preoperative COVID-19 diagnosis
Comparing the timing of surgery after COVID-19 diagnosis vs. 30-day mortality yielded the following results:
- 0 to 2 weeks – 9.1% mortality.
- 3 to 4 weeks – 6.9%.
- 5 to 6 weeks – 5.5%.
- 7 weeks or longer – 2.0%..
For comparison, the 30-day mortality rate for surgical patients without a preoperative COVID-19 diagnosis was 1.4%. A COVID-19 diagnosis more than 7 weeks before surgery did not make a significant difference on outcomes.
The ‘why’ remains unknown
The reasons for the association between a COVID-19 diagnosis and higher postoperative death rates remain unknown. However, Dr. Nepogodiev speculated that it could be related to “some degree of lung injury, even if patients are initially asymptomatic.”
Intubation and mechanical ventilation during surgery could exacerbate the existing lung injury, he said, thereby leading to more severe COVID-19.
In fact, Dr. Nepogodiev and colleagues found that postoperative pulmonary complications followed a pattern similar to the findings on death. They reported higher rates of pneumonia, acute respiratory distress syndrome, and unexpected reventilation in the first 6 weeks following a COVID-19 diagnosis. Again, at 7 weeks and beyond, the rates returned to be relatively the same as those for people who never had COVID-19.
“Waiting for 7 or more weeks may allow time for the initial COVID-19 injury to resolve,” Dr. Nepogodiev said.