Shock index and its variants as predictors of mortality in severe traumatic brain injury

Table 1 Characteristics of patients with severe head injury

	Survival (n = 49)		Non-survival (n = 22)		P value1
Age (years), mean ± SD	40.51	17.4	50.73	14.6	0.013
Days in MV, mean ± SD	28.76	14.6	14.36	16.8	0.001
Fasted days, mean ± SD	13.78	8.7	7.68	6.4	0.002
Days in hospital, mean ± SD	28.76	14.6	14.36	16.8	0.001
					P value2
Sex, n (%)					0.161
Male, n (%)	44	89.8%	17	77.3%
Female, n (%)	5	10.2%	5	22.7%
Injury type, n (%)					0.607
Closed	35	71.4%	17	77.3%
Open	14	28.6%	5	22.7%
Injury cause, n (%)					0.408
Fall	13	26.5%	10	45.5%
Transit accident	18	36.7%	4	18.2%
Assault	13	26.5%	6	27.3%
Gunshot	4	8.2%	1	4.5%
Other	1	2.0%	1	4.5%
Associated injuries, n (%)					0.658
None	36	73.5%	19	86.4%
Thoracic	4	8.2%	1	4.5%
Arms	1	2.0%	0	0.0%
Legs	5	10.2%	2	9.1%
Spine	3	6.1%	0	0.0%
Craniotomy procedure, n (%)					0.822
No	34	77.3%	15	68.2%
Yes	14	31.8%	7	31.8%
Body mass index (kg/cm²), n (%)					0.761
Underweight	4	8.2%	2	13.6%
Eutrophic	25	51.0%	0	54.5%
Overweight	14	28.6%	2	18.2%
Grade I Obese	6	12.2%	2	13.6%
Comorbidities, n (%)
COPD	0	0	2	9.1%	0.032
Asma	1	0.02	0	0.0%	0.513
T2DM	1	0.02	2	9.1%	0.172
SAH	4	8.2%	2	9.1%	0.897
EVA	1	0.02	1	4.5%	0.555
AD	2	4.1%	1	4.5%	0.928

¹Student’s t test.

²Pearson’s Chi-Square test.

MV: Mechanical ventilation; COPD: Chronic obstructive pulmonary disease; DM: Type 2 diabetes mellitus; SAH: Systemic arterial hypertension; EVA: Encephalic vascular accident; AD: Alzheimer's disease.

Table 2 Blood pressure, heart rate and different shock indexes (mean ± SD)

	Survival (n = 49)		Non-survival (n = 22)		P value
SBP-24 h (mmHg)	135.59	36.5	138.95	40.1	0.739
DBP-24 h (mmHg)	81.27	23.5	85.38	25.2	0.526
HR-24 h (bpm)	88.22	25.4	88.68	29.0	0.949
SBP-48 h (mmHg)	131.47	27.6	127.20	25.0	0.536
DBP-48 h (mmHg)	67.77	12.1	72.33	15.0	0.257
HR-48 h (bpm)	82.61	18.5	93.95	19.9	0.036
SI-adm	0.70	0.3	0.69	0.3	0.901
SI-48 h	0.65	0.2	0.79	0.3	0.03
rSI-adm	1.70	0.8	1.78	1.0	0.742
rSI-48 h	1.66	0.5	1.44	0.5	0.106
rSIG-adm	10.45	5.9	11.02	7.7	0.758
rSIG-48 h	10.26	4.8	9.29	4.8	0.452
AgeSIG-adm	28.02	16.8	34.40	17.1	0.152
AgeSIG-48 h	26.32	14.2	37.27	17.8	0.016

SBP: Systolic blood pressure; HR: Heart rate; DBP: Diastolic blood pressure; SI: Shock index; rSI: Reverse shock index; rSIG: rSI multiplied by the Glasgow Coma Score; AgeSIG: Age multiplied SI.

Table 3 Logistic regression and receiver operator curves analysis parameters

	Sig.	Exp(B)	95%CI for EXP(B)		Odds ratio (%)	AUC	P value
			Inferior	Superior
SI-adm	0.895	0.885	0.144	5.444	-11.5	0.487	0.864
SI-48 h	0.129	7.592	0.554	104.036	659.2	0.606	0.176
rSI-adm	0.727	1.107	0.626	1.956	10.7	0.517	0.832
rSI-48 h	0.194	0.436	0.125	1.527	-56.4	0.395	0.180
rSIG-adm	0.652	1.018	0.942	1.101	1.8	0.537	0.637
rSIG-48 h	0.641	0.973	0.867	1.092	-2.7	0.473	0.727
AgeSIG-adm	0.153	1.022	0.992	1.052	2.2	0.639	0.071
AgeSIG-48 h	0.015	1.044	1.008	1.082	4.4	0.727	0.003

SI: Shock index; rSI: Reverse SI; rSIG: rSI multiplied by the Glasgow Coma Score; AgeSIG: Age multiplied SI; AUC: Area under the curve.