Death following pulmonary complications of surgery before and during the SARS-CoV-2 pandemic: a comparative analysis of two prospective international cohort studies

Abstract Background: This study aimed to determine the impact of pulmonary complications on death after surgery both before and during the SARS-CoV-2 pandemic. Methods: A patient-level, comparative analysis of two, international prospective cohort studies: one pre-pandemic (January to October 2019) and the second during the SARS-CoV-2 pandemic (local emergence of COVID-19 up to 19 April 2020). Both included patients undergoing elective resection of an intra-abdominal cancer with curative intent across five surgical oncology disciplines. Case selection and rates of 30-day postoperative pulmonary complications were compared. The primary outcome was 30-day postoperative mortality. Mediation analysis using a natural effects model estimated the proportion of deaths during the pandemic attributable to SARS-CoV-2 infection. Results: This study included 7402 patients from 50 countries; 3031 (40.9%) operated pre-pandemic and 4371 (59.1%) during the pandemic. Overall, 4.3% (n=187/4371) developed postoperative SARS-CoV-2 in the pandemic cohort, with the pulmonary complication rate no different (7.1% (n=216/3031) versus 6.3% (n=274/4371), p=0.158) but mortality significantly higher (0.7% (n=20/3031) vs 2.0% (n=87/4371), p<0.001). There were higher adjusted odds of mortality in the pandemic than pre-pandemic (OR: 2.72, 95% CI: 1.58-4.67, p<0.001). In mediation analysis, 54.8% of excess postoperative deaths during the pandemic were estimated as attributable to SARS-CoV-2 (OR: 1.73, 95% CI: 1.40-2.13, p<0.001). Conclusions: Whilst providers may have selected patients with a lower risk profile for surgery during the pandemic, this did not mitigate the likelihood of death through SARS-CoV-2 infection. Care providers must urgently act to protect surgical patients from SARS-CoV-2 infection until universal vaccination is available.