Unruptured Cerebral Aneurysms: Evaluation and Management

Table 2

Summary of large studies evaluating the natural history of unruptured cerebral aneurysms.

Study design	Number of aneurysms and patients	Follow-up duration in years	Predictors of cerebral aneurysm rupture	Design flaws
International Study of Unruptured Intracranial Aneurysms (ISUIA) [12]: Retrospective Study in North America and Europe	1937 unruptured aneurysms in 1449 patients	8.3	(1) Size > 10 mm; (2) Posterior circulation and posterior communicating artery aneurysms	(1) Selection bias
International Study of Unruptured Intracranial Aneurysms (ISUIA) [12]: Prospective Observational Study in North America and Europe	2686 unruptured aneurysms in 1692 patients	4.1	(1) Size > 7 mm; (2) Previous subarachnoid hemorrhage from some other aneurysm; (3) Posterior circulation and posterior communicating artery aneurysms	(1) Selection bias; (2) Follow-up was <5 years for >50% of patients
Comprehensive Observational Cohort Study by Juvela and colleagues in Finland [13]	181 unruptured aneurysms in 142 patients	21	(1) Patient’s age (inversely); (2) Cigarette smoking; (3) Size > 10 mm	(1) Small total number of patients; (2) Homogeneity of the study population
The Unruptured Cerebral Aneurysm Study of Japan (UCAS): Prospective Cohort Study by Morita et al. [14]	6697 unruptured aneurysms in 5720 patients	Not available	(1) Size > 7 mm; (2) Location: anterior and posterior communicating arteries; (3) Presence of daughter sac	(1) Selection bias; (2) Homogeneity of the study population