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Risk factors for small intracranial aneurysm rupture identified
31 August 2010
MedWire News: Japanese researchers recommend that patients under the age of 50 years with hypertension and multiple intracranial aneurysms of at least 4 mm in diameter should be considered for treatment to prevent rupture at a later date.
They report that the annual risk for rupture for individuals with a single aneurysm less than 5 mm in diameter in their study was “quite low,” and considerably less than the complication rate reported if the aneurysm was treated.
However, the average annual risk for rupture in patients with multiple small aneurysms of this size was more than three times higher, and the 10- and 20-year lifetime probability of rupture occurring exceeded the complication risk associated with treatment.
The Small Unruptured Intracranial Aneurysm Verification (Suave) study included 374 patients with a total of 448 unruptured aneurysms less than 5 mm in diameter who were recruited at 12 Japanese hospitals between September 2000 and January 2004.
After a mean follow-up of 41.0 months, the average annual risk for rupture associated with small unruptured aneurysms was 0.54% overall, 0.34% for single aneurysms, and 0.95% for multiple aneurysms.
Significant predictors for the rupture of small aneurysms included the patient being aged less than 50 years (hazard ratio [HR]=5.23), aneurysm diameter of at least 4.0 mm (HR=5.86), hypertension (HR=7.93), and aneurysm multiplicity (HR=4.87).
Reporting in the journal Stroke, Tomosato Yamazaki (Mito Medical Center, Ibaraki) and colleagues say: “The current study showed the average annual risk of rupture of single-type unruptured aneurysms to be 0.34%/year.
But they add: “On the other hand, the annual risk of rupture of multiple-type unruptured aneurysms was 0.95%/year, triple that of single-type cases.”
The team calculates: “The 10-year and 20-year lifetime rupture probabilities of multiple unruptured aneurysms are 9.1% and 17.4%, respectively. These values exceed the risk of treating unruptured aneurysms.”
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