Use of failure-to-rescue after emergency surgery as a dynamic indicator of hospital resilience during the COVID-19 pandemic. A multicenter retrospective propensity score-matched cohort study

•Failure-to-rescue following emergency surgery experienced a two-fold increase during the COVID-19 pandemic peak.•There were sensitive differences among hospitals, not justified by patient profile or severity of pathology.•A significant greater increase was associated with higher-COVID-19 incidence and some hospital characteristics, including high basal-adjusted complication risk.•Failure-to-rescue could help to identify hospitals struggling to respond to ongoing challenges, guiding allocation of resources.