(New recommendation) Natural History and Outcome of aSAH Although the case fatality of aSAH remains high world- wide,5 mortality rates from aSAH appear to have declined in industrialized nations over the past 25 years.9,11,15,58,59 One study in the United States reported a decrease of 1% per year from 1979 to 1994.60 Others have shown that case fatality rates decreased from 57% in the mid-1970s to 42% in the mid-1980s,11 whereas rates from the mid-1980s to 2002 are reported to be anywhere from 26% to 36%.6,12,13,18,20,61,62 Mortality rates vary widely across published epidemiological studies, ranging from 8% to 67%.59 Regional variations become apparent when num- bers from different studies are compared. The median mortality rate in epidemiological studies from the United States has been 32% versus 43% to 44% in Europe and 27% in Japan.59 These numbers are based on studies that did not always fully account for cases of prehospital death. This is an important consideration because the observed decrease in case fatality is related to improvements in survival among hospitalized patients with aSAH. The mean age of patients presenting with aSAH is increas- ing, which has been noted to have a negative impact on survival rates.59 Sex and racial variations in survival may also play a role in the variable rates, with some studies suggesting higher mortality in women than in men9,11,60 and higher mortality in blacks, American Indians/Alaskan Natives, and Asians/Pacific Islanders than in whites.63 Available population-based studies offer much less infor- mation about the functional outcome of survivors. 