Table 2. Descriptive Statistics of Case and Control Groups.

Characteristic	Patients, %		Standardized difference, %
	Cases	Controls
No. of admissions	10 176	29 161	NA
No. of patient-days	126 374	119 020	NA
Hospital length of stay, mean (SD), d	15.0 (18.5)	6.9 (8.2)	NA
Unit length of stay, mean (SD), d	12.4 (16.3)	5.3 (6.2)	NA
Age, y
<65	47.3	49.0	2.8
≥65	52.7	51.0
Race and ethnicity
Non-White	33.1	32.7	0.7
White	66.9	67.3
Sex
Female	46.6	46.2	0.7
Male	53.4	53.8
Primary insurance
Public	69.4	69.5	0.3
Private	30.6	30.5
Total Charlson Comorbidity Index score at admission
0-1	28.1	31.2	5.6
≥2	71.9	68.8

Abbreviation: NA, not applicable.