Table 4. Subgroup analysis of the associations between BAR and 30-day all-cause mortality by multivariable Cox regression. Adjusted for age, gender and ethnicity, malignant cancer, severe liver disease, creatine, WBC, platelets, SOFA, mechanical ventilation and vasoactive use.

Subgroups	No. of patients	HR (95% CI)	P value	P value for interaction
Age (years)				0.89
<65	2,595	1.01 (1.00, 1.02)	0.04
≥65	2,861	1.02 (1.01, 1.03)	<0.001
Gender				0.83
Male	3,133	1.02 (1.01, 1.03)	<0.001
Female	2,323	1.02 (1.01, 1.03)	<0.001
Ethnicity				0.78
White	3,516	1.01 (1.01, 1.02)	<0.001
Black/African American	551	1.02 (1.00, 1.04)	0.03
Asian	158	1.03 (1.00, 1.06)	0.07
Unknown	1,231	1.01 (1.00, 1.02)	0.02
Congestive heart failure				0.40
No	3,506	1.02 (1.01, 1.02)	<0.001
Yes	1,950	1.01 (1.00, 1.02)	0.003
Renal disease				0.12
No	4,083	1.01 (1.01, 1.02)	<0.001
Yes	1,373	1.01 (1.00, 1.02)	0.003
Severe liver disease				0.57
No	4,813	1.02 (1.01, 1.02)	<0.001
Yes	643	1.01 (0.99, 1.02)	0.27
Malignant cancer				0.19
No	4,596	1.02 (1.01, 1.02)	<0.001
Yes	860	1.01 (1.00, 1.02)	0.007
Chronic pulmonary disease				0.48
No	3,870	1.01 (1.01, 1.02)	<0.001
Yes	1,586	1.02 (1.01, 1.03)	<0.001
Mechanical ventilation				0.09
No	1,801	1.03 (1.02, 1.04)	<0.001
Yes	3,655	1.01 (1.00, 1.02)	0.01
Vasopressor use				0.06
No	5,104	1.02 (1.01, 1.02)	<0.001
Yes	352	1.00 (0.98, 1.02)	0.91

BAR, blood urea nitrogen-to-albumin ratio; WBC, white blood cell; SOFA, sequential organ failure assessment; HR, hazard risk; CI, confidence interval.