INTRODUCTION: Most of the currently used prognostic models for COVID-19 are based on Western cohorts, but it is unknown whether any are applicable to patients with COVID-19 in Japan .
METHODS: This retrospective cohort study included 160 patients with COVID-19 who were admitted to the National Center for Global Health and Medicine between January 26 , 2020 and July 25 , 2020 . We searched PubMed for prognostic models for COVID-19 . The predicted outcome was initiation of respiratory support or death . Performance of the candidate models was evaluated according to discrimination and calibration . We recalibrated the intercept of each model with our data . We also updated each model by adding ß2-microglobulin (ß2MG) to the model and recalculating the intercept and the coefficient of ß2MG .
RESULTS: Mean patient age was 49.8 years , 68% were male , 88.7% were Japanese . The study outcomes occurred in 15 patients, including two deaths . Two-hundred sixty-nine papers were screened, and four candidate prognostic models were assessed . The model of Bartoletti et al . had the highest area under receiver operating characteristic curve (AUC) (0.88; 95% confidence interval 0.81-0.96). All four models overestimated the probability of occurrence of the outcome . None of the four models showed statistically significant improvement in AUCs by adding ß2MG .
CONCLUSIONS: Our results suggest that the existing prediction models for COVID-19 overestimate the probability of occurrence of unfavorable outcomes in a Japanese cohort . When applying a prediction model to a different cohort, it is desirable to evaluate its performance according to the prevalent health situation in that region.