CovidSurg Research Explained

The CovidSurg group aims to understand the impact of the COVID-19 pandemic on surgical patients and help surgeons and healthcare services adapt patient care to make it as safe as possible during and after the pandemic.

This page explains the CovidSurg research findings that are helping guide decisions for surgical patients and plan surgical services. The summaries in the dropdown boxes are designed to be accessible to patients, their families and the wider public audience.

The CovidSurg group has carried out two main ‘cohort’ studies tracking the outcomes of surgical patients. The first looked at patients diagnosed with COVID-19 around the time of their operation to understand their unique risks. The second is examining the outcomes for patients with cancer who have had surgery or should have had surgery if not for the pandemic. The team has also been assessing the influence of the pandemic on surgical services, including operation cancellations.

The findings of these studies are directly impacting on and informing patient health and surgical safety.

CovidSurg is committed to disseminating data quickly that can impact patient care. You can watch our Webinars here.

Planning for the Pandemic 

In March 2020, the CovidSurg group started work to identify evidence and experience from other surgeons in countries already affected by the coronavirus. They identified key actions that surgical services should take to minimise the impact and enhance safety during the pandemic. A Global Guidance document was published in the British Journal of Surgery.

Click here to access the full manuscript.

Context: In March 2020, surgeons worldwide urgently needed guidance on how to deliver surgical services safely and effectively during the COVID-19 pandemic.
Surgical teams needed to contribute to the COVID-19 response while continuing to care for emergency and urgent surgical patients. They needed to work with limited hospital beds, expect staff shortages and avoid the risks of in-hospital spread of the virus.

Aim: To identify key aspects of care, to safely deliver urgent surgery during the pandemic.

Strategy: First, searches were completed to find articles about management of surgical patients during pandemics. Second, surgeons and anaesthetists with first-hand pandemic experience were interviewed. Key challenges were identified and action plans proposed.

Impact: By gathering the best evidence and experiences, the study helps surgeons optimise care during the pandemic. This report helps surgical planning and promotes patient safety despite the challenging circumstances.

Results: The searches and interviews identified seven aspects of surgery that would need special attentions, to deliver safe surgery during the pandemic.

1. Planning for pandemics should be:

  • Part of routine planning at hospitals.
  • Led by a surgeon or anaesthetist with input from infection control experts.
  • Updated regularly according to international guidelines.
  • Rapidly activated when there is a pandemic threat, to quickly update hospital staff training.

2. Outpatient visits should be:

  • Replaced by telephone [or video] consultations where possible.
  • Postponed if care is non-urgent.
  • Undertaken at a specific date and time to minimise time spent in hospital, and ONLY when a physical visit for urgent diagnostic tests or care is essential.
  • Rescheduled if a patient displays symptoms of the pandemic illness.

3. Planned (Elective surgery) should be:

  • Reduced to free up beds and staff to care for pandemic patients and reduce the spread of infection.
  • Prioritised based on urgency and the risks to patients of any delay.
  • Modified to reduce operating times.
  • Postponed or if undertaken, keeping patients fully informed of benefits and risks.
  • Tracked so that the backlog of operations can be undertaken after the pandemic disease peak.

4. Cancer care should be:

  • Delivered carefully keeping in mind the risks of the disease worsening.
  • Continued as long as safely possible, according to hospital capacity.

5. Emergency surgical care should be:

  • Avoided where non-operative treatment is a reasonable option.
  • Undertaken with caution, due to the risks of complications and death if patients become infected with the virus. Only urgent, unavoidable surgery will go ahead.
  • Delivered by surgeons trained to
    • recognize possible COVID-19 infection.
    • test appropriately.
    • wear personal protective equipment to protect patients and themselves.
  • Delivered to patients with suspected or confirmed infection
    • in separate units.
    • with specific logistics planning for transfer between departments.
    • in an allocated operating theatre for COVID-19 positive patients.
  • Undertaken away from parts of the hospital caring for patients with COVID-19.

6. Patients with complications of COVID-19 after surgery should be:

  • Anticipated;
    • patients may have been in contact with the virus before, during or after their operation.
    • they may start showing symptoms while recovering.
    • they are more likely to become seriously ill if they get the virus.
  • Tested for the virus.
  • Isolated to stop virus spreading.
  • Cared for by specific team members.
  • Discharged home with clear instructions about how to avoid spreading the virus.

7. Surgical teams should:

  • Anticipate colleague sickness in their pandemic rotas.
  • Maintain social distancing.
  • Adopt teleconferencing in place of meetings.
  • Take into account colleagues at high risk who may need to shield, or with caring commitments.

Conclusion: Specific ‘pandemic-preparedness’ plans should be made in every hospital and regularly updated during any pandemic to best protect and care for surgical patients.

Having Surgery and Getting COVID-19

The first results from the ‘CovidSurg Cohort’ study, tracked the outcomes of surgical patients diagnosed with COVID-19 around the time of their operation. You can read a summary here of the first paper about death and breathing complications after surgery in patients infected with coronavirus (SARS-CoV-2). The paper was published in The Lancet. It was a massive team effort.

Click here to access the full manuscript 

Context: A new coronavirus (SARS-CoV-2) appeared in late 2019, rapidly spread across the world and resulted in the COVID-19 pandemic declared by the World Health Organisation on 11th March 2020. Very little was known of the effects of the virus on surgical patients who are particularly vulnerable with risks from an operation as well as risks of infection with the virus.

Aims: To find out what happens to patients after an operation if they are infected with the virus either just before or in the first month after their operation. Specifically, we wanted to find out how many patients die after surgery, how many develop breathing complications, and identify key risk factors.

Impact: The rates of breathing complications and death associated with COVID-19 around the time of operation are important to help surgeons and patients make the safest treatment decisions.

Strategy: Surgeons from hospitals worldwide were invited to take part in this study. In 235 hospitals from 24 countries surgeons and researchers identified all patients who had an operation and tested positive for coronavirus around the time of surgery. Patients who were suspected to have the virus (but not tested) were also included as testing was not widely available in the early stages of the pandemic.

Team members collected anonymous patient data about age, gender, underlying illnesses and their operation. Patient records were followed up for 30 days after the operation. Researchers recorded if a patient had died or been diagnosed with one of three serious breathing problems: pneumonia (lung infection); unexpected ventilation (an artificial breathing machine); or acute respiratory distress syndrome (ARDS, where the lungs become badly inflamed and cannot provide the body with enough oxygen).


What did the study find?

1128 patients operated between 1 Jan and 31 March 2020 were included in the study. 53 percent of patients were men, and nearly 50% were 70 years or older. The majority of patients underwent emergency surgery (74%), and most had major operations (74%). About a quarter of patients had cancer surgery (24%).

· 268 of 1128 patients (23.8%) died within 30 days of their operation.
· Just over half of patients (51.2%) had serious breathing complications. In this group the death rate was much higher at 38%.
· With pneumonia, the death rate was 38%; those requiring unexpected ventilation had a death rate of 41% and in patients with ARDS, the death rate was 63%.

Who is at highest risk?

We identified patients and operation characteristics that increased patients’ risk of death. We found that male patients, age 70 years or over, those with underlying health problems; undergoing a ‘major’ operation, emergency surgery or cancer surgery all led to the higher risks of death.

What were the rates of serious breathing complications and death before the pandemic?

Patients with SARS-CoV-2 after an operation have overall, substantially higher rates of breathing problems and death than any studies have shown before the pandemic. A national audit in the UK (called ‘NELA’) looking at emergency abdominal surgery, showed 16.9% risk of death overall and 23.4% in frail patients >70years old. An international study (by GlobalSurg) in 58 low and middle-income countries showed 14.9% death rate in patients identified as high risk, after the same type of surgery. The death rates of patients with the virus after an operation are extremely high and similar to the death rates of the small group of severe COVID-19 patients who need intensive care.

Conclusion: The high risks of breathing complications and death have highlighted that surgical patients who contract coronavirus are particularly vulnerable. We recommend that surgeons ‘raise the threshold’ for surgery during the pandemic – surgeons should postpone operations or select non-operative management options where available. Furthermore strategies should be developed to reduce in-hospital SARS-CoV-2 transmission so minimising the risk of postoperative complications.

Operation Cancellations

The high rates of breathing complications and death identified among patients operated during the pandemic, who also caught the virus, supported early pandemic decisions to postpone elective surgery. However the risks of postponing tens and hundreds of thousands of operations are significant. To quantify the burden, the CovidSurg group published a modelling study in the British Journal of Surgery.

Click here to access the full manuscript.

Context: COVID-19 has led to worldwide disruption to surgical services. Cancellations have expanded waiting lists and new patients continue to be added. Operations cancelled early in the pandemic had benefits in:

  • Protecting patients from possible infection with COVID-19 in hospital
  • Preserving precious personal protective equipment
  • Releasing ventilators, ward and critical care beds for emergency care of COVID-19 patients
  • Releasing anaesthetists, theatre staff and surgeons for redeployment to other departments

Aim: To estimate the expected number of cancelled operations worldwide in the peak 12 weeks of COVID-19 pandemic disruption.

Impact: This evidence can be used to assist healthcare providers plan and create strategies for surgical services in the pandemic recovery period.

Strategy: We invited surgeons from hospitals worldwide to give expert estimates of the proportions of planned (elective) surgery that would be cancelled in the peak 12 weeks of the pandemic. 359 hospitals in 71 countries took part. Data was analysed using the usual numbers of operations per country, to calculate total expected cancellations by country and specialty.


What did the study find?

  • Estimates for proportions of cancelled surgery were highest for benign (non-progressive or non-cancerous) conditions (71-87% cancelled).
  • The proportion of cancelled cancer surgery was lowest in the most developed countries. There was a wide range in rate of cancer surgery cancellations, (23-77%).
  • Planned obstetric operations were cancelled in 17-38%.

What does that mean in real numbers?

  • Approximately 28.4 million operations were cancelled in the peak 12 weeks of the COVID-19 pandemic, that is 2.4 million per week.
  • In 11 countries, >50,000 operations were cancelled per week.
  • Of the cancellations, we estimate:
    • >90%, 25.6million were for benign disease
    • 8%, 2.3million were for cancer
    • 1.6%, 0.4million were for obstetrics.
  • Orthopaedic surgery was most frequently cancelled.
  • Results were broken down to country-level. The most cancellations were predicted in Europe and Central Asia where there is normally higher surgical activity. The least in Sub-Saharan Africa.
  • Estimates for least to worst case disruption reported 20-44million cancellations.

What will this mean going forward?

If surgical services increased activity by 20% above pre-pandemic levels they would take 45 weeks (>10 months) to clear the backlog of operations.

How accurate are these estimates?

Surgeons in countries that had not yet reached pandemic peak reported expected proportions of cancelled surgery.

Results are presented with best and worst case disruption scenarios.
This study uses published estimates of the number of operations that take place per country if that country does not publish data.

If regional outbreaks last longer or shorter than 12 weeks, estimates may not match local disruption but can be adjusted to aid recovery planning.

Conclusion: To clear growing waiting lists for surgery, there will need to be significant government investment. For example, in the UK the operation backlog would cost >£2billion to clear (based on £4000 per operation).
While patients await surgery, they risk worsening disease. This may result in patients being unable to work, which would further increase the costs of the pandemic to society.
If future COVID-19 outbreaks occur, surgical services should be ready to continue to operate in specifically designed environments to protect patients from COVID-19.
Research to identify systems to perform surgery safely despite the pandemic could help minimise future cancellations and reduce the impact on population health.

COVID-19 free Surgical Pathways 

To continue to offer cancer surgery during the pandemic as safely as possible, some health systems and hospitals adapted their services to offer ‘COVID-19 free surgical pathways’. As redesign is expensive it must be supported by sound evidence. This study, the first data from the CovidSurg Cancer study, examines the rates of breathing complications, COVID-19 infection and death after surgery, in hospitals with specially designed pathways versus those operated without defined pathways. It has been published in the Journal of Clinical Oncology.

Click here to access the full manuscript.

Context: Providing rapid treatment for cancer surgery is important to avoid worsening disease whilst waiting for an operation. COVID-19 has increased the risks associated with surgery. In some places, surgical units have been organised to strictly separate patients having surgery from areas where patients with COVID-19 are treated. These are known as COVID-19 free surgical pathways.

Aim: To measure how often patients get serious breathing complications after cancer surgery during the pandemic, depending on whether they are treated in a COVID-19 free surgical pathway or a hospital without this setup.

Impact: Healthcare providers can use this evidence, to invest in the right facilities, to continue to undertake operations and deliver care as safely as possible.

Strategy: We invited surgeons from hospitals worldwide to contribute to this study. 445 hospitals in 54 countries took part. Patients were included if they had surgery from the time COVID-19 arrived in that region until 19th April 2020. A COVID-19 free surgical pathway meant patients undergoing surgery were separated in operating theatres, critical care and inpatient wards, from areas of the hospital treating COVID-19. If any one area was shared with patients with COVID-19, the patient was considered to be treated in a unit with no defined pathway.

International team members collected anonymous patient data about age, gender, underlying illnesses, type of cancer and the operation. Patient records were followed up for 30 days after the operation. Researchers recorded if a patient had died or had been diagnosed with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2, the virus which causes COVID-19) or one of three serious breathing problems: pneumonia (lung infection); unexpected ventilation (an artificial breathing machine); or acute respiratory distress syndrome (ARDS, where the lungs become badly inflamed and cannot provide the body with enough oxygen).

We expected that healthier (lower risk) patients would be treated more often in COVID-19 free surgical pathways, with fewer resources e.g. intensive care units. We tested the data to make sure the higher number of low risk patients treated within COVID-19 free pathways did not mislead our conclusions.


What did the study find?

9171 adults who had cancer surgery were included. 27% were operated within surgical pathways and 73% with no defined pathway. The patients operated within COVID-19 free pathways tended to be younger with fewer medical problems. Three quarters of all operations were major surgery.

  • 2.2%, ~1/45 patients operated within COVID-19 free pathways had breathing complications.
  • 4.9%, ~1/20 patients operated in a hospital with no defined pathway had breathing complications.
  • Having an operation within a COVID-19 free pathway resulted in fewer breathing complications even after direct comparison of patients with the lowest risks from each group.
  • SARS-CoV-2 infection was detected in 2.1% patients after an operation in a COVID-19 free pathway. This compares with detection in 3.6% patients following an operation with no defined pathway.
  • 1.5% patients died within 30 days of their operation. Deaths were more common in patients with serious breathing problems and SARS-CoV-2 infection.
  • Death rate was lower within COVID-19 free pathways.

Who is at highest risk?

Increased risk of breathing problems was identified among:

  • Older patients
  • Male patients
  • Patients with other medical problems particularly with cardiac (heart) risks or existing respiratory (lung) disease
  • Advanced cancer
  • Patients undergoing major surgery
  • High local levels of COVID-19

What else did we learn?

In the early phase of the pandemic only 27% of these patients had a SARS-CoV-2 test before surgery. With improved reliability of tests, screening will play a role to minimise operating on patients with asymptomatic or presymptomatic COVID-19. The benefits of COVID-19 free surgical pathways were greatest where there were high local levels of COVID-19.

Conclusion: Death after surgery was mostly related to serious breathing complications, which were high with post-operative COVID-19, and low in COVID-19 free surgical pathways. To protect patients, COVID-19 free surgical pathways should be used during this and future COVID-19 outbreaks to ensure planned cancer surgery can continue.

What about patients with previous SARS-CoV-2 infection?

The first CovidSurg Cohort study results highlighted the dangers of having an operation and contracting COVID-19 around the same time. The data from the CovidSurg Cancer study allowed us to take an early look at a sample of patients having planned surgery with a previous positive SARS-CoV-2 swab. It was published as a letter in the British Journal of Surgery.

Click here to access the full manuscript.

Context: Surgeons globally are working through a backlog of at least 28 million operations that were delayed during the first COVID-19 pandemic wave. Inevitably, many patients who have already been infected with the virus will need surgery. At present we don’t know when is the safest time to have an operation after SARS-CoV-2 infection.

Aim: To identify relationships between a previous positive SARS-CoV-2 swab and serious breathing problems after surgery.

Impact: Identifying the optimal timing for surgery following SARS-CoV-2 infection will help surgeons and patients plan surgery, protect patients and save resources.

Strategy: Patients undergoing planned cancer surgery during the pandemic up to 24 May 2020, with a previous positive SARS-CoV-2 swab were identified from the CovidSurg Cancer study data. Their data was compared to patients without previous positive swabs to explore their outcomes.

Results: Data came from patients treated in 78 different hospitals in 16 countries. 112 patients with a previous positive swab were matched with 448 patients with no previous positive swab. A higher rate of serious breathing complications occurred after operation in patients with previous infection. This was lower when the operation occurred > 4 weeks following a positive swab.

What does this mean?
The small number of patients with previous SARS-CoV-2 and the methods of matching in this study are imperfect, so these results are not conclusive. However they give an indication of the risks of previous SARS-CoV-2 for surgical patients.

Conclusion: Currently, for patients planning surgery, it is advisable to delay surgery at least 4 weeks from the time of a positive swab. Future, larger study data will try to establish the safest time for surgery after infection. To help guide surgical patients and healthcare professionals to understand risk, we hope to be able to examine differences between previous symptomatic and asymptomatic infections.

Testing for SARS-CoV-2 infection before surgery

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 British Journal of Surgery evaluates the associations between SARS-CoV-2 testing before operations and serious breathing problems afterward.

Click here to access the full manuscript.

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.

Sharing our research accessibly means producing different media to communicate our results to ensure surgeons, hospitals and patients can all access the results to make decisions based on real data.

To view our video abstract please click here.

The British Journal of Surgery‘s Cutting Edge blog also published our lay summary here.

Bowel cancer surgery during the first part of the pandemic 

Previous CovidSurg Cohort and CovidSurg Cancer study papers have looked at the impact on patients of undergoing surgery during the COVID-19 pandemic, whether that was major/minor or elective/emergency surgery. However, this broad overview did not focus on different body systems nor address the specific risks linked with operating on individual organ systems. The CovidSurg Cancer study data was used in this paper to look at the impact of the pandemic on patients having bowel cancer surgery to identify specific risks surgeons should be aware of and to assist surgical services to plan for safe surgery within safe surgical pathways.
It was published in Colorectal Disease.

Click here to access the full manuscript.

Context: The pandemic led to a large number of non-urgent operations being cancelled in an effort to reduce infection in patients who would have attended hospital. The pandemic also diverted equipment and people from their normal working environments to assist in the increased demand on intensive care facilities coping with COVID-19 patients.
Guidelines were published to guide surgeons to care for patients who required urgent surgery. These guidelines prescribed more risk averse types of operations to avoid the need for intensive care support afterward and reduce the risks of death if a complication did occur. One recommendation was to avoid creating bowel joins (anastomoses) afte