Table 1.
Study population.a
| Data set | Non–COVID-19 | COVID-19 | P value (non–COVID-19 vs COVID-19 test sets)b | ||||||||||
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|
Training 2014-2018 | Validation 2014-2018 | Testing 2019 | Testing 2020 |
|
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| Encounters, n | 105,457 | 26,089 | 33,472 | 637 | N/Ac | ||||||||
| Patients, n | 62,392 | 15,597 | 23,368 | 600 | N/A | ||||||||
| Age (years), median (IQR) | 60.2 (46.5-70.8) | 60.4 (46.7-71.2) | 61.0 (47.0-71.5) | 61.8 (49.6-72.0) | .02 | ||||||||
| Race, n (%) | |||||||||||||
|
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White | 86,522 (82.0) | 21,647 (83.0) | 27,036 (80.8) | 329 (51.6) | <.001 | |||||||
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Black | 12,344 (11.7) | 2861 (11.0) | 4214 (12.6) | 220 (34.5) | <.001 | |||||||
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Asian | 2145 (2.0) | 504 (1.9) | 686 (2.0) | 29 (4.6) | <.001 | |||||||
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Otherd | 4446 (4.2) | 1077 (4.1) | 1536 (4.6) | 59 (9.3) | <.001 | |||||||
| Female sex, n (%) | 53,225 (50.5) | 13,048 (50.0) | 16,760 (50.1) | 282 (44.3) | .003 | ||||||||
| Event ratee, n (%) | 4236 (4.0) | 1007 (3.9) | 1337 (4.0) | 155 (24.3) | <.001 | ||||||||
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Death | 920 (0.9) | 232 (0.9) | 277 (0.8) | 16 (2.5) | <.001 | |||||||
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ICUf transfer | 2979 (2.8) | 717 (2.7) | 1000 (3.0) | 139 (21.8) | <.001 | |||||||
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Mechanical ventilation | 1330 (1.3) | 299 (1.1) | 352 (1.1) | 49 (7.7) | <.001 | |||||||
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Cardiac arrestg | 143 (0.1) | 37 (0.1) | 56 (0.2) | N/A | N/A | |||||||
aPatients were subset into one of four study cohorts: a training set for learning model parameters, a validation set for model structure and hyperparameter tuning, a holdout test set for evaluation, and a final test set composed of patients testing positive for COVID-19. Values are based on individual hospital encounters.
bP values were calculated across the two test sets using a Mann-Whitney U test for continuous variables (age) and a chi-square test for categorical variables.
cN/A: not applicable.
dOther races comprising less than 1% of the population each were incorporated under the “Other” heading.
eThe event rate represents a composite outcome indicating that one of the following events occurred: death, ICU transfer, mechanical ventilation, and cardiac arrest. The individual frequencies of these adverse events are also reported and represent the number of cases where each particular outcome was the first to occur. Please see the section Outcomes for the procedure of calculating these targets.
fICU: intensive care unit.
gCardiac arrest was not used as a target in the COVID-19 positive population, as the manually adjudicated data is not yet available at the time of writing.