Mortality Rate of Subarachnoid Hemorrhage
The mortality rate of subarachnoid hemorrhage is approximately 45% at 30 days, with the majority of deaths occurring within the first few days after the initial hemorrhage. 1
Overall Mortality Statistics
The 30-day mortality rate for all patients who suffer SAH is 45%, based on population-based studies, with most deaths concentrated in the initial days following hemorrhage 1
Approximately 12% of patients die before receiving any medical attention, highlighting the devastating nature of the initial bleed 1
The in-hospital mortality rate for SAH patients admitted through emergency departments is approximately 33% 1
The case fatality rate is approximately 50% overall when including pre-hospital deaths 1, 2
Temporal Pattern of Deaths
The timing of death after SAH follows a predictable pattern, with the initial hemorrhage being the most lethal phase:
61% of all deaths occur within the first 2 days of onset, with the vast majority (21 of 22 early deaths) attributable to the initial hemorrhage itself 3
The initial hemorrhage alone accounts for approximately 19% of all deaths at 3-month follow-up 4
Causes of Death
Deaths from SAH can be attributed to four major categories, each contributing roughly equally:
Initial hemorrhage effects: 19-23% of deaths - the direct devastating impact of the initial bleed on brain tissue 1, 4
Rebleeding: 22-23% of deaths - with a case fatality rate of 70% for patients who experience rebleeding 1, 4
Delayed cerebral vasospasm: 23% of deaths - though this plays a relatively minor role in overall mortality compared to earlier beliefs 4, 3
Medical (non-neurologic) complications: 23% of deaths - including cardiac, pulmonary, renal, and hepatic complications 4
Critical Prognostic Factors
The severity of the initial hemorrhage is by far the most important determinant of mortality:
Patients with SAH volume ≤15 cm³ have dramatically better survival, with only 3 of 29 such patients dying within 30 days in one population study 3
Clinical grade on admission strongly predicts outcome, with worse neurological status associated with higher mortality 1
Age, sex, time to treatment, and medical comorbidities (hypertension, atrial fibrillation, heart failure, coronary disease, renal disease) all influence mortality 1
Rebleeding as a Preventable Cause
Rebleeding represents the most important preventable cause of death in hospitalized SAH patients:
The risk of ultra-early rebleeding (within 24 hours) may be as high as 15%, considerably higher than previously recognized 1
70% of ultra-early rebleeds occur within 2 hours of the initial SAH 1
The rebleeding rate is 4% on the first day, then 1-2% per day over the subsequent 4 weeks 1
Impact of Hospital Volume
Treatment at high-volume centers significantly reduces mortality:
30-day mortality is 39% at low-volume hospitals (<10 SAH patients annually) versus 27% at high-volume hospitals (>35 patients annually) 1
The lowest-volume hospitals have mortality rates of 49% compared to 32% at highest-volume hospitals 1
Common Pitfalls
Avoid confusing aneurysmal SAH with traumatic SAH - traumatic SAH has different management priorities and does not require aneurysm repair or nimodipine 5
Do not underestimate the contribution of medical complications - pulmonary edema (23% incidence), cardiac arrhythmias (30% incidence), and other systemic complications equal the mortality contribution of vasospasm, rebleeding, or initial hemorrhage individually 4
Recognize that delayed vasospasm, while important, contributes to only a small fraction of deaths (approximately 2 of 36 deaths in population studies), contrary to its prominent role in clinical discussions 3