Table 1.

Participating health care systems’ overall characteristics and the number and period of chart reviews performed for this study.

Participating site	Hospitals, n	Inpatient discharges per year, n	Number of chart reviews performed, n	Chart review time period, start date-end date
BIDMCa	1	40,752	400	March 2020-March 2021
MGBb	10	163,521	406	March 2020-July 2021
NWUc	10	103,279	70	March 2020-February 2021
UPITTd	39	369,300	247	April 2020-August 2021

^aBIDMC: Beth Israel Deaconess Medical Center.

^bMGB: Mass General Brigham.

^cNWU: Northwestern University.

^dUPITT: University of Pittsburgh/University of Pittsburgh Medical Center.