Risk factors associated with rupture:
(1) female gender (relative risk 2.1)
(2) symptomatic aneurysms (relative risk 8.2)
(3) size > 10 mm (relative risk 5.5)
(4) located in the posterior circulation (relative risk 4.1)
The annual risk of rupture for an asymptomatic aneurysm <= 10 mm was about 0.7% per year.
Additional factors associated with rupture but with lower relative risks:
(1) older age (1.7 for 60-79 years of age vs 40-59)
(2) "additional" aneurysm (one found unruptured when evaluating a ruptured aneurysm; relative risk 1.7 vs asymptomatic aneurysm)
For the implementation, I made up a risk score by adding the relative risks after rounding the values. This approach has not be tested or validated.
