Table 1.

Defined terms for asthma exacerbation prediction.

Term	Definition
Index date	The date of the first diagnosis of asthma in a patient’s EHRa
Exacerbation date	The date of the first diagnosis of asthma exacerbation after the index date
Case group	Patients with asthma and later asthma exacerbations within 365 days and satisfying the inclusion and exclusion criteria
Control group	Patients with asthma but without exacerbations within 365 days and satisfying the inclusion and exclusion criteria
Prediction date	Training set: for the case group, the visit date before the exacerbation date; for the control group, the penultimate visit date within 365 days: Testing set A: the fifth visit starting from the index date Testing set B: defined analogously to the training set
Observed time window	The time window between the index date and the prediction date

^aEHR: electronic health record.