Pre-operative testing for SARS-CoV-2 infection

Research in plain English

Scientific research can be challenging to follow, especially for those who are not experts in the field. There is lots of interest in COVID-19 from the public. The authors of the paper published in the BJS have provided a plain English summary to help people understand the work.

Background

As we continue in and between subsequent pandemic waves, and patients are booked for surgery, the CovidSurg cancer study data can help to identify where services can best spend resources to protect patients. This paper, published in the BJS evaluates the associations between SARS-CoV-2 testing before operations and serious breathing problems afterward.

SARS-CoV-2 swab testing before planned surgery reduces serious breathing complications

Context

At least 28 million operations were delayed during the first COVID-19 pandemic wave. As we resume operating, we need the ability to identify patients with pre-symptomatic infection and postpone surgery to keep those patients safe. We also need to use resources wisely by testing in situations where it will likely provide a benefit.

Aim

To understand the value of preoperative SARS-CoV-2 testing to prevent serious breathing problems after surgery.

Impact

To maximise the benefits for patients and guide the use of resources, this study looks at where and when swab testing can change patient outcomes.

Strategy

Surgical team members in 432 hospitals in 53 countries collected anonymised data for all patients having planned cancer surgery during the pandemic up to 19 April 2020. We included all patients with data about preoperative testing. Patients suspected of having the infection pre-operatively were excluded. Researchers recorded if a patient died or had serious breathing problems up to 30 days after their operation.

Results

2303/8784 patients (23%) were tested for SARS-CoV-2 before their operation. 1458 had a swab test, 521 a CT scan of their chest and 324 had both tests. 6746 major operations and 1087 minor operations were performed in high SARS-CoV-2 risk areas and a minority of operations took place in low risk areas.

Overall, 4% of patients experienced serious breathing problems following surgery. The rate was higher in patients with no test or CT scan-only testing. At least one negative swab before operation reduced the risk of serious breathing problems after surgery. Having repeated swabs did not add extra benefit.

The data showed that swab testing reduced breathing problems in high risk COVID areas but not in low risk areas. It also showed that a swab before major surgery reduced breathing problems but not before minor surgery. 

How many patients must be swabbed to prevent one patient having serious breathing problems?

To prevent one patient having serious breathing problems after major surgery, in a high risk area, 18 patients had to be swabbed; 48 had to be swabbed before minor surgery in a high risk area. This increased to 73 patients swabbed before major or 387 before minor surgery in low risk areas, to prevent one patient having breathing problems.

Some evidence also suggested there was a lower death rate among patients who were swabbed before their surgery.

Conclusion

The study group was able to recommend that ‘A single preoperative swab should be performed for patients with no clinical suspicion of COVID-19 before major surgery in both high and low risk areas and before minor surgery in high risk population areas’. 

Swab testing before surgery is likely to benefit patients by identifying pre-symptomatic or asymptomatic COVID-19 infection prior to admission. A positive swab result triggers operation delay, protects patients from severe breathing problems after surgery and helps protect other patients from in-hospital infection. Swabs together with other strategies, should be used to protect patients from COVID-19 during hospital care.

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