Risk Factors for Three Phases of 12-Month Mortality in 1657 Patients from a Defined Population After Acute Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE: To analyze the impact of factors known after admission on mortality attributable to aneurysmal subarachnoid hemorrhage (SAH) resulting from saccular intracranial aneurysm (IA). METHODS: Data of 1657 consecutive patients admitted alive within 24 hours after aneurysmal SAH to Kuopio Neurosurgery during the years 1980-2007 from a defined population were analyzed. RESULTS: Aneurysmal SAH caused excess mortality for 12 months, after which other causes of death became dominant. The 12-month mortality curve on a logarithmic time scale indicated acute (first 3 days), subacute (4-30 days), and delayed (1-12 months) mortality, with cumulative rates of 11% at 3 days, 22% at 30 days, and 27% at 12 months. The acute mortality was predicted by Hunt & Hess (H&H) grades IV-V, ruptured aneurysm >= 15 mm, and acute subdural hematoma. Age, gender, intracerebral hemorrhage (ICH), and time period of admission were not independent risk factors. Advanced age, H&H grades IV-V, intraventricular hemorrhage (IVH), giant ruptured saccular IA, ruptured saccular IA on the internal carotid artery or the basilar artery bifurcation, and severe hydrocephalus in different combinations predicted subacute and delayed mortality. Patients in good condition on admission had a mortality rate of only 3.5% at 12 months, regardless of age. CONCLUSIONS: Sequelae of aneurysmal SAH were the leading cause of death for 12 months. Mortality analysis of this period displayed three phases with distinct independent risk factors. These data support the creation of prognosticators for prediction on admission of the everyday individual risk of death until 12 months after aneurysmal SAH.