Table 2.

Univariate and multivariable analyses for the relationship between the candidate risk factors and 30-day mortality in the primary cohort

Variables	Univariate model			Multivariable model
	HR	95% CI	P value	HR	95% CI	P value
Age	1.042	1.031 to 1.053	<0.001	1.033	1.022 to 1.045	<0.001
Male	0.549	0.418 to 0.721	<0.001	0.763	0.574 to 1.015	0.063
Weight	0.989	0.981 to 0.996	0.002
Private insurance	0.353	0.249 to 0.502	<0.001
Heart rate	1.022	1.015 to 1.029	<0.001	1.016	1.008 to 1.023	<0.001
MAP	0.985	0.977 to 0.993	<0.001
Haemoglobin	0.882	0.828 to 0.940	<0.001
WBC	1.064	1.049 to 1.079	<0.001	1.029	1.014 to 1.044	<0.001
BUN	1.025	1.021 to 1.030	<0.001	1.014	1.008 to 1.020	<0.001
Bicarbonate	0.842	0.819 to 0.866	<0.001	0.904	0.875 to 0.933	<0.001
Creatinine	1.257	1.181 to 1.338	<0.001
Potassium	1.394	1.193 to 1.630	<0.001	1.169	0.975 to 1.403	0.092

HRs were estimated by Cox proportional hazards regression. All statistical tests were two-sided. The selection of the final prediction model was performed with a backward stepwise selection process.

BUN, blood urea nitrogen; MAP, mean arterial pressure; WBC, white blood cell count.