Table 2. Multivariable Cox Proportional Hazards Analysis of 1-Year Mortality After Heart Transplantation (N = 18,396).

Covariate	HR	95% CI	P value
Pre-transplant ICU staya	1.5	1.2, 2.0	0.003
Age group (years)
< 1	0.8	0.5, 1.3	0.434
2 - 11	0.5	0.3, 0.8	0.002
12 - 18	0.4	0.3, 0.7	0.001
19 - 29	0.9	0.7, 1.3	0.685
30 - 39	1.2	0.9, 1.6	0.153
40 - 49	Ref.	-	-
50 - 59	1.3	1.0, 1.6	0.025
60 - 69	1.8	1.5, 2.2	< 0.001
≥ 70	2.1	1.5, 3.0	< 0.001
Interaction of ICU stay with age group (years)
< 1	0.7	0.4, 1.1	0.139
2 - 11	0.6	0.3, 1.1	0.110
12 - 18	0.8	0.4, 1.6	0.536
19 - 29	0.8	0.5, 1.4	0.472
30 - 39	0.8	0.5, 1.2	0.276
40 - 49	Ref.	-	-
50 - 59	0.9	0.6, 1.3	0.536
60 - 69	0.7	0.5, 1.0	0.067
≥ 70	0.6	0.3, 1.2	0.171
Female gender	1.1	1.0, 1.3	0.025
Race
Non-Hispanic White	Ref.	-	-
Non-Hispanic Black	1.4	1.2, 1.5	< 0.001
Hispanic	1.1	0.9, 1.3	0.310
Other	1.1	0.8, 1.3	0.657
BMI category
Underweight	0.8	0.7, 1.1	0.163
Normal weight	Ref.	-	-
Overweight	1.1	1.0, 1.3	0.015
Indication for transplant
Congenital heart disease	Ref.	-	-
Hypertrophic cardiomyopathy	0.5	0.3, 0.7	< 0.001
Ischemic cardiomyopathy	0.4	0.4, 0.5	< 0.001
Non-ischemic cardiomyopathy	0.4	0.3, 0.4	< 0.001
Restrictive cardiomyopathy	0.6	0.5, 0.8	< 0.001
Valvular heart disease	0.4	0.2, 0.6	< 0.001
Other	0.3	0.2, 0.5	< 0.001
Mechanical ventilation	1.8	1.5, 2.2	< 0.001
Mechanical circulatory support
None	Ref.	-	-
Extracorporeal membrane oxygenation	3.1	2.4, 4.0	< 0.001
Ventricular assist device	1.4	1.2, 1.6	< 0.001
Inotrope use	1.0	0.9, 1.1	0.567
Dialysis on waitlist	2.2	1.8, 2.8	< 0.001
Bilirubin > 2 mg/dL	1.6	1.4, 1.9	< 0.001
Infection requiring intravenous antibiotics	1.2	1.1, 1.4	0.001
Allograft ischemia time (h)
< 2	Ref.	-	-
2 - 4	1.0	0.8, 1.2	0.878
> 4	1.3	1.1, 1.6	0.001

^aHazard ratio (HR) reflects estimate for ages 40 - 49 years. The interaction terms estimate how this HR is modified in other age groups. BMI: body mass index.