Table 4.

Features used in our model and their importance.

Feature	Importance based on average impurity decrease
Hour of EDa disposition	0.42
Age in days	0.40
Whether the patient has any other barrier to learning	0.39
Length of ED stay in minutes	0.38
Number of laboratory tests ordered during the ED visit	0.37
Heart rate	0.37
Diastolic blood pressure	0.36
Gender	0.35
Temperature	0.35
Respiratory rate	0.34
Number of radiology studies ordered during the ED visit	0.34
Insurance category	0.34
Number of X-rays ordered during the ED visit	0.34
Systolic blood pressure	0.34
Weight	0.33
Chief complaint	0.32
SpO2b	0.32
Wheezing	0.32
Retractions	0.29
Number of consults during the ED visit	0.28
Whether the patient is up-to-date with his/her immunizations	0.27
Race	0.27
Enterovirus infection	0.25
Respiratory syncytial virus infection	0.24
Coinfection	0.24
Prior hospitalization	0.22
Prior intubation	0.22
Dehydration	0.20
Language barrier to learning	0.20
Rhinovirus infection	0.20
Prematurity	0.18
History of bronchopulmonary dysplasia	0.16
History of eczema	0.15

^aED: emergency department.

^bSpO₂: peripheral capillary oxygen saturation.