Table 1.

Metadata studied within a COVID-19 cohort.

Metadata (Data type)	Description		Data Reference
Median EHR length (Years)	Difference in years between the first recorded test date (either influenza or SARS-CoV-2) and first recorded visit, any type.		Data quantity
Missingness (Count)	“Unknown” demographic(s) (i.e., any incomplete age, self-reported race, gender) data element in the RD.		Data quantity
Data density (Categorical, institution-specific)	No Visits	Individuals with no visit(s) billed prior to the week before the first test date.	Data quality
	No Primary Care Visit	Non-primary care visit(s) billed before the first test date.
	Medical Home	At least one primary care visit, identified by local site IDs, billed before the first test date.
Data density (Binary, not institution-specific)	Presence of a CPT code that indicates a ‘Comprehensive history’ was taken prior to or on the day of the first SARS-CoV-2 test (Appendix Table A4)		Data quality

COVID-19: Coronavirus disease 2019; EHR: Electronic health record; RD: RD: Research Derivative, a database of clinical information curated from the EHR at Vanderbilt University Medical Center and restructured for research; CPT: Current procedural terminology.