Table 3

Risk factors associated with subarachnoid haemorrhage*

Variable	Univariate			Multivariate
Variable	RR	95% CI	P value	OR	95% CI	P value
Age<56	1.509	1.150 to 1.979	0.002
Epidural AVF	1.465	1.080 to 1.989	0.052
Perimedullary AVF	1.898	1.554 to 2.318	<0.001
Radicular AVF	1.551	1.208 to 1.992	0.004
Dural AVF	0.83	0.455 to 0.747	<0.001
Fistula location: foramen magnum	0.490	0.244 to 0.981	0.012
Fistula location: C-2	1.343	1.023 to 1.763	0.055
Arterial feeder: dural branch of vertebral artery	0.679	0.528 to 0.873	0.005	0.334	0.146 to 0.766	0.010
Arterial feeder: Radicular artery	1.551	1.208 to 1.992	0.004
Arterial feeder: anterior spinal artery	1.819	1.458 to 2.270	<0.001
Arterial feeder: lateral spinal artery	1.739	1.371 to 2.206	0.002
Arterial feeder: Ascending pharyngeal artery	0.490	0.244 to 0.981	0.012
Drain: ascending intradural drainage	3.796	2.572 to 5.603	<0.001	11.096	4.856 to 25.356	<0.001
Drain: descending intradural drainage	0.301	0.216 to 0.419	<0.001	0.222	0.112 to 0.441	<0.001
Drain: epidural drainage	1.713	1.341 to 2.189	0.004	11.099	2.429 to 50.720	0.002
Aneurysmal structure	1.971	1.553 to 2.502	<0.001	2.807	1.102 to 7.149	0.031