Prediction of hospital mortality in intensive care unit patients from clinical and laboratory data: A machine learning approach

Table 1 Descriptive and univariate comparative analyses for numerical predictive variables according to outcome

Variable	mean ± SD		U value	P value
	Death outcome, n = 338	Survival outcome, n = 749
Age	63.4 ± 15.7	60.1 ± 16.1	111072	< 0.001
Disease score	1.3 ± 0.8	1.2 ± 0.7	121505.5	0.110
Eye opening (GCS)	2.0 ± 1.2	2.5 ± 1.2	97325.0	< 0.001
Heart rate	114.3 ± 34.9	111.1 ± 31.1	117672.0	0.031
Hematocrit	31.7 ± 8.3	32.8 ± 7.3	116749.0	0.02
MAP	84.7 ± 53.9	87.4 ± 48.7	108432.0	< 0.001
Max albumin	2.7 ± 0.7	2.8 ± 0.6	109136.0	< 0.001
Max bilirubin	2.2 ± 3.8	1.2 ± 1.8	98589.5	< 0.001
Max BUN	40.0 ± 25.2	33.8 ± 24.5	102300.0	< 0.001
Max calcium	8.0 ± 0.9	8.1 ± 0.8	117155.0	0.024
Max creatinine	2.6 ± 2.0	2.0 ± 1.9	96278.5	< 0.001
Max DBP	92.0 ± 23.1	94.8 ± 21.5	116162.0	0.015
Max glucose	231.4 ± 113.0	210.1 ± 105.2	11090.0	< 0.001
Max HCO3	21.0 ± 5.1	23.3 ± 4.8	94750.0	< 0.001
Max hemoglobin	11.7 ± 2.5	11.7 ± 2.3	124619.0	0.341
Max INR	2.1 ± 1.3	1.6 ± 0.8	83944.0	< 0.001
Max lactate	7.3 ± 5.5	3.2 ± 2.8	62255.5	< 0.001
Max platelets	189446.7 ± 98687.9	198186.9 ± 96842.7	120773.5	0.113
Max potassium	4.7 ± 0.9	4.5 ± 0.8	106603.0	< 0.001
Max sodium	142.1 ± 6.7	140.9 ± 5.4	113894.0	0.004
Max SBP	147.5 ± 29.3	151.1 ± 26.2	113747.5	0.004
Max SpO2	99.6 ± 1.5	99.8 ± 0.6	119714.5	0.005
Max WBC	17442.9 ± 10269.3	15302 ± 8516	111218.5	0.001
Min albumin	2.5 ± 0.7	2.7 ± 0.6	101997.5	< 0.001
Min bilirubin	1.9 ± 3.3	1.1 ± 1.7	101177.5	< 0.001
Min BUN	34.2 ± 22.9	29.0 ± 21.0	106584.5	< 0.001
Min calcium	7.4 ± 0.9	7.7 ± 0.9	98668.5	< 0.001
Min creatinine	2.08 ± 1.7	1.6 ± 1.3	99935.0	< 0.001
Min glucose	104.6 ± 47.0	110.7 ± 38.1	111941.5	0.001
Min HCO3	17.0 ± 5.5	20.6 ± 5.5	79747.5	< 0.001
Min hemoglobin	10.3 ± 2.7	10.8 ± 2.4	111370.0	0.001
Min INR	1.8 ± 0.9	1.5 ± 0.6	89909.5	< 0.001
Min lactate	4.7 ± 4.0	2.1 ± 1.58	69894.5	< 0.001
Min platelets	157252 ± 94655.6	177120.8 ± 90595.7	110075.0	< 0.001
Min potassium	3.8 ± 0.8	3.8 ± 0.7	125962.0	< 0.001
Min SBP	75.4 ± 20.3	84.9 ± 19.6	92919.0	< 0.001
Min sodium	137.9 ± 6.1	138.2 ± 5.5	121722.5	0.155
Min WBC	13247.1 ± 8505.4	12.7 ± 6.9	122208.5	0.181
Min DBP	38.7 ± 14.9	44.9 ± 12.7	93559.5	< 0.001
Min SpO2	81.3 ± 19.0	88.0 ± 12.0	94624.5	< 0.001
Motor response (GCS)	2.9 ± 2.2	4.3 ± 2.0	83488.5	< 0.001
PaCO2	40.0 ± 13.9	39.5 ± 11.6	124352.0	0.321
PaO2	137.4 ± 102.3	130.9 ± 82.4	121043.0	0.124
pH	7.3 ± 0.1	7.3 ± 0.1	109784.0	< 0.001
Respiratory rate	31.2 ± 15.1	27.5 ± 14.9	107284.5	< 0.001
Temperature	35.2 ± 1.9	36.2 ± 1.4	80674.5	< 0.001
Verbal response (GCS)	1.9 ± 1.5	2.3 ± 1.7	109666.5	< 0.001

BUN: Blood urea nitrogen; DBP: Diastolic blood pressure; GCS: Glasgow coma scale; INR: International normalized ratio; MAP: Medium Arterial Pressure; PaCO₂: Partial pressure of carbonic gas in arterial blood; PaO₂: Partial pressure of oxygen in arterial blood; SBP: Systolic blood pressure; SpO₂: Saturation of peripheral oxygen; WBC: White blood cells.