Table 3.

Characteristics of the Patients.

Characteristic	ICUs with Nighttime Intensivists (N = 14,424)	ICUs without Nighttime Intensivists (N = 51,328)	P Value
Age — yr			<0.001
Median	66	62
Interquartile range	54–76	51–74
Female sex — %	42.4	44.6	<0.001
Race — no. (%)*			<0.001
White	11,888 (82.4)	40,481 (78.9)
Black	538 (3.7)	5,376 (10.5)
Other	1,265 (8.8)	1,750 (3.4)
Data missing	733 (5.1)	3,721 (7.2)
Admission source — no. (%)			<0.001
Emergency department	4,625 (32.1)	22,495 (43.8)
Operating room	4,760 (33.0)	13,371 (26.1)
Medical or surgical ward	2,807 (19.5)	10,725 (20.9)
Transfer	1,263 (8.8)	3,832 (7.5)
Other	969 (6.7)	905 (1.8)
Reason for ICU admission — no. (%)			<0.001
Surgery	3,878 (26.9)	10,290 (20.0)
Cardiac disorder	2,253 (15.6)	7,865 (15.3)
Respiratory disorder	1,867 (12.9)	7,074 (13.8)
General medical disorder	1,233 (8.5)	6,152 (12.0)
Sepsis	1,047 (7.3)	4,769 (9.3)
Trauma	718 (5.0)	3,862 (7.5)
Neurosurgery	615 (4.3)	1,681 (3.3)
Cardiac arrest	496 (3.4)	1,534 (3.0)
Other	2,317 (16.1)	8,101 (15.8)
Acute physiology score†			<0.001
Median	36	38
Interquartile range	24–53	25–56
Active treatment on day of ICU admission — no. (%)‡	9,509 (65.9)	34,911 (68.0)	<0.001
Mechanical ventilation on day of ICU admission — no. (%)	6,687 (46.4)	22,811 (44.4)	<0.001
Emergency surgery — no. (%)	534 (3.7)	2,630 (5.1)	<0.001
Length of hospital stay before ICU admission — days			<0.001
Median	0.50	0.46
Interquartile range	0.20–1.10	0.12–1.06
In-hospital death — no. (%)	1,842 (12.8)	6,872 (13.4)	0.053

^*Race was determined on admission by the admitting clinical team.

^†The acute physiology score is a measure of severity of illness ranging from 0 to 252, with higher scores indicating more severe illness and a higher risk of death.

^‡Active treatment was defined as any of 33 active life-supporting intensive care treatments.¹⁴