Table 1.

Patient characteristics in group 1 and group 2.

	Group 1		Group 2		Total			P value
	n = 40		n = 20		n = 60
	Number	Mean	Number	Mean	Number	Mean	%
Age (years)
≤15 years	5	31.5	3	33.5	8	33.0	13.3	0.800ω
16–30 years	14		7		21		35.0
>30 years	21		10		31		51.7
Gender
Male	31	NA	15	NA	46	NA	76.7	0.910ψ
Female	9		5		14		23.3
Initial Glasgow score
3 to 5	15	7.22	11	7.25	26	7.23	43.4	0.540ω
6 to 8	14		3		17		28.3
>8	11		6		17		28.3
Preoperative pupillary abnormality
No	23	NA	3	NA	26	NA	43.3	0.031 ψ
Unilateral dilated	11		10		21		35
Bilateral dilated   (absent corneal reflex)	6  (2)		7  (4)		13  (5)		21.7  (8.3)
Multiple trauma
Yes	17	NA	9	NA	26	NA	43.3	0.930χ
No	23		11		34		56.7
Circumstances of trauma
Road accident	26	NA	10	NA	36	NA	60.0	NA
Fall from a great height	3		5		7		11.7
Fall from a small height	11		5		17		28.3
Initial CT analysis of the lesions according to the Marshall classification
I	14	NA	0	NA	14	NA	23.3	0.003 ω
II	12		0		12		20.0
I + II	26		0		26		43.3
III	1		0		1		1.7
IV	13		4		17		28.3
III + IV	14		4		18		30.0
Evacuated mass	0		16		16		26.7
Interval between trauma and decompressive craniectomy
<6 h	4	2.35 days	16	0.55 days	20	1.75 days	33.3	<0.001 ω
6 h to 24 h	7		0		7		11.7
24 h to 7 days	26		4		30		50.0
>7 days	3		0		3		5.0

Preoperative characteristics of patients in group 1 and group 2 are expressed by number in each category and the mean value or percentage with respect to the total sample size (%). Values for the 2 groups were compared by statistical tests evaluating the P value (α < 5%).

^ωWelch t-test; ^ψMann-Whitney test; ^χChi-square test.

MVA: motor vehicle accident; VKA: vitamin K antagonist; PAI: platelet aggregation inhibitor; NA: not applicable.

The bold font highlights the most significant parameters.