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We studied subarachnoid hemorrhage in the population of Rochester, Minnesota,for the 40-year period from 1945 through 1984.The average annual incidence rate of subarachnoid hemorrhage in Rochester has remained constant at approximately 11 per 100,000 population.Age-specific incidence rates increased with age.However,the average annual mortality rate for subarachnoid hemorrhage in Rochester has shown a decreasing trend,from 6.8 per 100,000 population in 1955-1964 to 4.3 in 1975-1984.It is likely that this is due to a decrease in case-fatality rates from 57%in 1945-1974 to 42%in 1975-1984(p=0.10).This decreasing trend was also evident in annual mortality rates from subarachnoid hemorrhage for US white men and women. The reason for the improved case-fatality rate is unclear,but it may be related to changes in management.The interval from onset of subarachnoid hemorrhage to surgery decreased from a median of 12 days in 1975-1979 to 2 days in 1980-1984,and of those who survived to receive medical attention, more patients received some form of medical treatment in 1980-1984.Whether either or both of these changes have led to the decrease in the case- fatality rate is uncertain. |
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