30-day postoperative mortality and the effects of hospital preparedness during the COVID-19 pandemic: a pooled analysis of prospective international cohort studies

Background: Surgical services were poorly prepared for the COVID-19 pandemic, leading to widescale disruption to elective activity. This study aimed to identify actionable priorities to strengthen pandemic preparedness of surgical and hospital systems. Methods: This study pooled data from three international, prospective cohort studies including patients who had a positive SARS-CoV-2 test result in the seven days before or within 30 days after surgery. Patients were included across four pandemic time periods: Period 1 (January-May 2020), Period 2 (June-July 2020), Period 3 (October 2020), and Period 4 (December-March 2022). The primary outcome measure was 30-day postoperative mortality. Hierarchical logistic regression models were developed to explore association between pandemic periods (primary analysis) and hospital-level preparedness (secondary analysis) on 30-day postoperative mortality. Hospital preparedness was classified in to poorly-, moderately-, and highly-prepared tertiles based on Surgical Preparedness Index (SPI) score. Findings: A total of 31,751 patients were included from 1589 hospitals and 102 countries. From Period 1 through to Period 4 there was a decrease in the proportion of patients aged ≥70 years and with ASA grades 3-5.30-day postoperative mortality fell from Period 1 (18.4% [1378/7502]), Period 2 (9.9% [219/2234], adjusted odds ratio (aOR) 0.65, 95% confidence interval (CI) 0.53-0.78), Period 3 (10.5% [246/2427], aOR 0.60, 95% CI 0.50-0.71), through to Period 4 (5.8% [1132/19,588], aOR 0.33, 95% CI 0.30-0.37). During Period 4, SARS-CoV-2 vaccinated patients had lower mortality compared to unvaccinated patients (4.9% [603/12,361] versus 7.4% [529/7178], aOR 0.49, 95% CI 0.42-0.57). Compared to poorly-prepared hospitals (11.2% [1019/9071]), moderately-prepared (9.4% [857/9071], aOR 0.84, 95% CI 0.75-0.94) and highly-prepared hospitals (5.8% [530/9071], aOR 0.70, 95% CI 0.62-0.80) had lower mortality. Interpretation: Postoperative mortality decreased over the course of the COVID-19 pandemic and was lower in better prepared hospitals. Hospitals are critical national infrastructure and strengthening their preparedness by developing formal pandemic plans, establishing patient and procedure prioritisation protocols, and ring-fencing surgical beds would ensure safer surgical care during future pandemics. Funding: National Institute for Health and Care Research, United Kingdom.