Table 2

Operator and site factors versus the occurrence of a hemorrhagic stroke (n=13)

					SAH or ICH
Factor	No of sites oroperators	No of patients	SAH (n (%))	ICH (n (%))	n (%)	p Value	Difference (95% CI)†
SAMMPRIS site enrollment
High (≥12)	12	111	1 (0.9)	2 (1.8)	3 (2.7)	0.043	−7.1% (−14.9% to 0.6%)
Low (<12)	36	102	5 (4.9)	5 (4.9)	10 (9.8)
High enrolling registry site
No	38	132	5 (3.8)	5 (3.8)	10 (7.6)	0.38	3.9% (−4.0% to 10.5%)
Yes	10	81	1 (1.2)	2 (2.5)	3 (3.7)
Primary specialty of interventionist
Radiology	39	115	4 (3.5)	3 (2.6)	7 (6.1)	0.071	1: 3.3% (−6.6% to 11.7%)
Neurosurgery	18	72	0 (0)	2 (2.8)	2 (2.8)		2: −9.3% (−34.3% to 4.8%)
Neurology	6	26	2 (7.7)	2 (7.7)	4 (15.4)		3: 12.6% (−37.1% to 1.9%)
Credentialing: No of study devices
<10	30	71	2 (2.8)	2 (2.8)	4 (5.6)	0.99	−0.7% (−7.3% to 8.1%)
≥10	33	142	4 (2.8)	5 (3.5)	9 (6.3)
Credentialing: No of aneurysm stents
<6	29	116	3 (2.6)	4 (3.4)	7 (6.0)	0.99	−0.2% (−7.7% to 6.8%)
≥6	34	97	3 (3.1)	3 (3.1)	6 (6.2)
No of years in practice
<8	28	104	5 (4.8)	3 (2.9)	8 (7.7)	0.40	3.1% (−3.8% to 10.8%)
≥8	35	109	1 (0.9)	4 (3.7)	5 (4.6)
No of SAMMPRIS PTAS cases
<3	31	43	2 (4.7)	2 (4.7)	4 (9.3)	0.40	4.0% (−3.8% to 17.2%)
≥3	32	170	4 (2.4)	5 (2.9)	9 (5.3)

*p Value for Fisher's exact test comparing percentages among groups.
†Difference between percentages, calculated as first group − second group, except for primary specialty (1: radiology − neurosurgery, 2: radiology − neurology, 3: neurosurgery − neurology).
‡Total in both groups exceeds 63 interventionists because individual interventionists had patients in both groups.
ICH, intraparenchymal hemorrhage; PTAS, percutaneous transluminal angioplasty and stenting; SAH, subarachnoid hemorrhage.