UCAS, Japan - 2012
The Natural Course of Unruptured Cerebral Aneurysms in a Japanese Cohort | NEJM
In this paper[1], the authors enrolled newly identified, unruptured saccular cerebral aneurysms of 3 mm or more in patients aged 20 years or older in Japan from January 2001 to April 2004. They concluded that the natural course of unruptured cerebral aneurysms varies according to the size, location, and shape of the aneurysm.
Study Specifics
- Journal: New England Journal of Medicine
- Publication history: June 28, 2012
- Study type: prospectively enrolled study
- Enrollment
- Interval: January 2001-April 2004
- Age: 20 years of age or older
- Aneurysm: 3 mm or more in the largest dimension
- Exclusion
- Previous intracranial hemorrhage of unknown or untreated cause
- mRS > 2
- Fusiform or dissecting aneurysms
- Cavernous aneurysms
- Total patients: 5720
- Male: 1915 (33.5%)
- Female: 3805 (66.5%)
- Mean age: 62.5±10.3 years
- Total aneurysms: 6697
- Male: 2165 (32.3%)
- Female: 4532 (67.7%)
- Aneurysm characteristics
- Incidental: 91%
- Location
- MCA: 36%
- ICA: 34%
- Size
- Mean: 5.7±3.6 mm
- Follow-up
- Interval: up to 8 years
- Period: 11,660 aneurysm-years
- Ruptured: 111 patients (1.94%)
- Annual rate of rupture: 0.95% [0.79-1.15]
- Rupture risks (hazard ratio and [95% confidence interval])
- Increased size (using 3-4 mm in size as the reference)
- 5-6 mm: 1.13 [0.58-2.22]
- 7-9 mm: 3.35 [1.87-6.00]
- 10-24 mm: 9.09 [5.25-15.74]
- 25 mm or larger: 76.26 [32.76-177.54]
- Location (MCA aneurysms as the reference)
- ACOM: 2.02 [1.13-3.58]
- PCOM: 1.90 [1.12-3.21]
- Shape
- With a daughter sac: 1.63 [1.08-2.48]
- Increased size (using 3-4 mm in size as the reference)
- Ruptured aneurysms
- Death: 39 (35%)
- mRS 3-5: 32 (29%)
- Surgical intervention before rupture
- 2722 patients
- 3050 aneurysms
- Median: 48 days from initial visit
- Limitation
- Unknown number of patients who declined to participate
- More than 2,000 small aneurysms were treated surgically
- Included only Japanese patients who has a higher risk of subarachnoid hemorrhage
Reference Points
- The old patients had larger aneurysms.
- The risk of rupture was significantly increased for all aneurysms that were 7 mm or larger.
- In patients with multiple aneurysms, each aneurysm is not associated with an increased risk of rupture.
- Thrombosed or calcified aneurysms were often large and had an increased tendency to rupture (small number of cases).
- The overall rate of rupture of cerebral aneurysms was 0.95% annually.
- A history of subarachnoid hemorrhage, former or current smoking, the presence of multiple aneurysms, and hypertension, did not significantly affect the risk of rupture in this cohort.
