More than 50% of coronavirus patients who underwent surgery suffered from post-operative pulmonary complications, a new study suggests.

Researchers say clinicians must carefully balance risk of complications linked to SARS-CoV-2 infection with risks of delaying surgery, and suggest the threshold for surgery should be raised compared to normal practice.

In the study, published in The Lancet, post-operative pulmonary complications occurred in 51.2% of coronavirus patients who underwent surgery.

These complications included conditions such as pneumonia, acute respiratory distress syndrome, and/or unexpected postoperative ventilation.

Among patients with SARS-CoV-2 infection who underwent surgery, 23.8% died within 30 days.

Of those with pulmonary complications, 38%, 219/577 died within 30 days of their surgery.

SARS-CoV-2 is a specific virus that can cause Covid-19.

The study also identified factors associated with worse outcomes.

As well as being male or aged 70 or older, patients with comorbidities and those undergoing cancer surgery, emergency or major surgery were among the most vulnerable.

Researchers conducted an observational study of 1,128 patients across 24 countries between January 1 and March 31 this year.

The study included data from hospitals mainly in Europe and America with ongoing coronavirus outbreaks.

Lead author Dr Aneel Bhangu, from the University of Birmingham in the UK, said: “Although the risks associated with Covid-19 need to be carefully balanced against the risks of delaying surgery for every individual patient, our study suggests that the thresholds for surgery should be raised, compared to normal practice.

“Medical teams should consider postponing non-critical procedures and promoting other treatment options, which may delay the need for surgery or sometimes avoid it altogether.”

Dr Ana Minaya-Bravo, of the Hospital Universitario del Henares and Universidad Francisco de Vitoria in Spain, said: “When hospitals resume routine surgery, it’s likely it will take place in environments that remain exposed to SARS-CoV-2.

“Hospital-acquired infection will remain a challenge, but strategies are urgently required to minimise it, as well as to minimise the risk of pulmonary complications for infected patients whose surgery cannot be delayed.

“Future studies should assess the role that preoperative testing could play in deciding which patients are selected for surgery.”

The patients included in the study had tested positive for SARS-CoV-2 within seven days leading up to their operation, or 30 days following surgery.

The researchers gathered data on 30-day post-surgery death rates and pulmonary complications.

They say their findings suggest the rates for mortality and pulmonary complications are higher than those associated with even the highest risk groups before the pandemic.

However, they note that it was not feasible for participating hospitals, many of which were experiencing significant stress due to the pandemic, to collect data on all patients undergoing surgery.

Therefore comparisons were not made during the same period against patients not infected with the virus.

Instead, the authors provide comparisons to pre-pandemic mortality rates and pulmonary complications, which should be interpreted with caution.

For example, a 2016 study across 58 countries reported 30-day mortality of 14.9% in a high-risk subgroup who underwent emergency, major surgery of the abdomen, and a 2019 study across 211 hospitals from 28 European countries found a pulmonary complication rate of 8%.

The authors note that although this is the first multi-country study which reaches across all surgical specialities, it has some limitations including that the data were collected at the early stages of the pandemic, when routine testing was not available at all locations.