Owing to challenges of clinical data collection during an epidemic, missing data are common, with choice of predictors influenced by data availability.40 Complete case analysis often leads to exclusion of a substantial proportion of the original sample, subsequently leading to a loss of precision and power.44 However, the assessment of missing data on model performance in novel covid-19 risk stratification scores has been limited37 or unexplored,3840 potentially introducing bias and further limiting generalisability to other cohorts. We found discriminatory performance in both derivation and validation cohorts remained similar after the imputation of a wide range of variables,41 further supporting the validity of our findings.