Incidence and outcome of subarachnoid haemorrhage: A retrospective population based study

Abstract

Objectives - The purpose was to define the incidence and case fatality rates of subarachnoid haemorrhage in the population of Devon and Cornwall. Methods - A retrospective population based design was employed with multiple overlapping methods of case ascertainment. A strict definition of subarachnoid haemorrhage was used. Age and sex specific incidence rates and relative risks for death at different time intervals are calculated. Results - Eight hundred cases of first ever subarachnoid haemorrhage were identified; 77% of cases were verified by CT, 22% by necropsy, and 1% by lumbar puncture. The incidence rates are higher than those previously reported in the United Kingdom. The age standardised incidence rate (/100 000 person-years) for females was 11.9 (95% confidence interval (95% CI) 9.5-15.0), for males 7.4 (5.4-10.0), and the total rate was 9.7 (7.5-12.6). The case fatality rates at 24 hours, 1 week, and 30 days were 21 (18-24)%, 37 (33-41)%, and 44 (40-49)% respectively. The relative risk for death at 30 days for those over 60 years:under 60 years was 2.95 (2.18-3.97). Conclusion - The incidence of subarachnoid haemorrhage in the United Kingdom is higher than previously reported. Three quarters of the mortality occurs within 3 days.