Relationship Of Aneurysmal Subarachnoid Haemorrhage And Climatic Conditions: A Retrospective Population-Based Study

Abstract

The objective of this study was to investigate the relationship between climatic conditions and aneurysmal subarachnoid haemorrhage (SAH). All patients with a diagnosis of SAH in the years 1992 1996 were identified. Data on these patients were obtained from a retrospective population-based study. Days with and without incidents were compared with data obtained from the Met Office; hourly barometric pressure changes, temperature, and humidity. Groups were compared with student's t test and the X 2 test for continuous variables and proportions respectively. Eight hundred cases of SAH were identified in the time period studied. There were 516 (64%) women and 284 men. The mean age at diagnosis was 61 (SD ± 15) years. Forty six percent of patients were over 65 years of age. SAH was more likely to occur on days with higher barometric pressure (P 0.031) however; the actual pressure differences were negligible. There was no relationship between temperature, humidity, and SAH. There was no seasonal variation in the incidence of SAH. There was no association between the severity of SAH and climatic conditions or the day of the week. SAH is less likely to occur over the weekend particularly Saturday 0.735 (0.611-0.885), (relative risk (95% confidence interval). SAH was more likely to occur on Tuesday with a relative risk of 1.153 (1.001 1.327). There is a statistically significant relationship between SAH and barometric pressure but not with either temperature or humidity. The day of the week does influence the incidence of SAH. The underlying reasons remain uncertain.