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 |