Table 1.

Metadata for clinical data sources in derivation dataset (ALHS)

Data Source	Number of Records	Number of Individuals	Extraction Date	Data Specification Date Range
Primary Care Prescribing*	4 709 231	47 095	October 2018	January 2009–April 2017
Primary Care Encounters*	11 766 100	49 307	March 2018	January 2000–November 2017
Accident & Emergency	1 831 789	500 321	November 2017	June 2007–September 2017
Hospital Inpatient Admissions	1 668 957	342 838	August 2018	January 2000–March 2017
Mortality	NA	91 758	May 2018	January 2000–March 2017

*Records available for subset of study population with asthma diagnosis only.