Recent COVID-19 infection puts surgical patients at higher blood clot risk

Digital illustration of a blood vessel
Patients diagnosed with current or previous SARS-CoV-2 are more likely to develop postoperative VTE than those with no history of COVID infection.

Surgical patients who have recently had COVID-19 are more likely to develop potentially fatal post-operative blood clots, a new global study reveals.

Researchers discovered that patients diagnosed with current or previous SARS-CoV-2 are more likely to develop postoperative venous thromboembolism (VTE) than those with no history of COVID infection.

VTE has been described as the number one preventable cause of death in hospitalised patients. In this study, VTE was independently associated with 30-day mortality with 5 times increased risk of death within 30 days after surgery in patients who develop VTEs.

Patients hospitalised with COVID-19 have previously been shown to have a high risk of VTE - between 9% and 26% despite the use of preventative drugs, and as high as 31% in patients within critical care settings. This study confirms an increased risk in patients hospitalised for surgery also.

Led by experts at the University of Birmingham, surgeons and anaesthetists from around the world worked together as part of the NIHR-funded COVIDSurg Collaborative to analyse data from 128,013 patients in 1,630 hospitals across 115 countries. The team published its findings in Anaesthesia.

The research team is calling for surgeons around the world to be on the lookout for VTE - following routine measures to help prevent the condition occurring, such as using appropriate drugs when bleeding risk is minimal and lowering the threshold for diagnostic testing in patients presenting with signs of VTE.

Routine postoperative care of surgical patients should include interventions to reduce VTE risk in general, and further research is needed to define the optimal protocols for VTE prevention and treatment for surgical patients in the setting of SARS-CoV-2 infection.

Co-author Elizabeth Li, clinical research fellow at the University of Birmingham, commented: “People undergoing surgery are already at higher risk of VTE than the general public, but we discovered that a current or recent SARS-CoV-2 infection was associated with greater risk of postoperative VTE.

“Most surgical patients have risk factors for VTE, including immobility, surgical wounds and systematic inflammation; the addition of SARS-CoV-2 infection may further increase this risk.”

Unlike medical patients, those people having surgery undergo an operative procedure artificially producing a wound that increases the risk of bleeding and initiates a series of inflammatory responses known to alter haemodynamics and coagulation.

Co-author Mr Aneel Bhangu, from the University of Birmingham, commented: “The impact of surgery on coagulation and early reports of increased risk of VTE in COVID-19 patients means there is a need to define VTE risk specifically in patients undergoing surgery. This will help clinicians and policymakers around the world construct future systems of identifying and minimising VTE risk in surgical patients with active or prior SARS-CoV-2 infection.

“Routine postoperative care of surgical patients should include interventions to reduce VTE risk in general, but further research is needed to define the best protocols for VTE prevention and treatment in this setting.”

Researchers examined data from adult patients, aged 18 and over, undergoing elective or emergency surgery from any specialty.

They defined four categories of patient: no SARS-CoV-2; peri-operative SARS-CoV-2 (diagnosed seven days before to 30 days after surgery); recent SARS-CoV-2 (diagnosed 1–6 weeks before surgery); or previous SARS-CoV-2 (diagnosed seven weeks or longer before surgery). VTE was defined as either deep vein thrombosis (DVT) or pulmonary embolism (PE).

A positive SARS‐CoV‐2 diagnosis was based on a patient having one or more of the following: a positive PCR test; a positive rapid antigen test; CT scan indicating infection; positive immunoglobulin G or immunoglobulin M antibody test; or clinical diagnosis where no swab test or CT scan were available.

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