Table 6. Comparison of the efficacy and safety of the chronological groups (1997–2003 versus 2006 to 2009 and 2012 to 2014) regarding the endovascular procedure.

Chi-Square tests examine the 0-Hypothesis H₀ that there is no difference regarding the rate of endovascular cases (n = 115) in the comprehensive group of 1997–2003 (n = 361) compared to the rate of endovascular cases (n = 137) in the comprehensive recent coiling group (n = 281) (coiling 2006–2009 and 2012–2014). Moreover Fisher-exact tests and Chi-Square tests examine the 0-Hypothesis H₀ that there is no difference regarding the rates of symptomatic ischemic stroke, occlusion rate, rebleeding, direct mortality and reinterventions between the two chronological groups (“Endovascular 1997–2003” versus “Endovascular 2006–2009 and 2012–2014”).

Endovascular treatment	Endovascular 1997–2003	Endovascular 2006–2009 and 2012–2014	OR	95% CI	p
Overall n = 252	115 of 361 (31.9%)	137 of 281 (48.8%)	0.49	0.36–0.68	< 0.0001
Initial symptomatic ischemic stroke	18 (15.7%)	27 (19.7%)	0.76	0.39–1.46	0.40
Permanent symptomatic ischemic stroke (one-year follow-up)	16 (13.9%)	21 (15.3%)	0.89	0.44–1.80	0.75
Initial subtotal occlusion	22 (19.1%)	20 (14.6%)	1.38	0.71–2.69	0.34
Initial incomplete occlusion	8 (7.0%)	9 (6.6%)	1.06	0.40–2.85	1.00
Complete occlussion	65 of 102 (22.3 months) (63.7%)	73 of 114 (13.1 months) (64.0%)	0.99	0.57–1.72	1.00
Re-bleeding (one-year follow-up)	7 (6 early) (6.1%)	3 (3 early) (2.2%)	2.90	0.73–11.46	0.19
Direct mortality	3 (2.6%)	4 (2.9%)	0.89	0.20–4.06	1.00
Reintervention (one-year follow-up)	16 (7 microsurgical clipping) (13.9%)	7 (1 microsurgical clipping) (5.1%)	3.00	1.19–7.58	0.017