Table 3.

Subgroup analysis stratified by age.

Variables	Age < 65y				Age ≧ 65 y
	Total n	Events	HR (95%CI)	P value	Total n	Events	HR (95%CI)	P value
With BA dolichosis	18	1	0.712 (0.079–6.408)	0.762	21	8	7.319 (1.525–35.123)	0.013
Without BA dolichosis	40	4	Ref	NA	34	2	Ref	NA

BA, basilar artery; HR, Hazard ratio; CI, confidence interval; NA, not applicable.