Abstract
BackgroundMost spontaneous subarachnoid hemorrhages (SAH) occur unexpectedly and independently of classical risk factors. In the light of increasing climate variability and change, we investigated weather and rapid weather changes as possible short-term risk factors for SAH.MethodsSeven hundred ninety one patients admitted to three major hospitals in Germany for non-traumatic SAH with a determinable onset of SAH symptoms were included in this hospital-based, case-crossover study. The effects of atmospheric pressure, relative air humidity, and ambient temperature and their 24 h changes on the onset of SAH under temperate climate conditions were estimated.ResultsThere was no association between the risk of SAH and 24 h weather changes, mean daily temperature or mean relative air humidity in the overall population. For every 11.5 hPa higher mean daily atmospheric pressure, the risk of SAH increased by 15% (OR 1.15, 95% confidence interval (CI) 1.01–1.30) in the entire study population with a lag time of three days.ConclusionOur results suggest no relevant association between 24 h-weather changes or absolute values of ambient temperature and relative humidity and the risk of SAH. The medical significance of the statistically weak increase in SAH risk three days after exposure to high atmospheric pressure is unclear. However, as the occurrence of stable high-pressure systems will increase with global warming and potentially affect SAH risk, we call for confirming studies in different geographical regions to verify our observations.
Highlights
Most spontaneous subarachnoid hemorrhages (SAH) occur unexpectedly and independently of classical risk factors
Additional data obtained from patient files included age, sex and aneurysmal size,the World Federation of Neurological Surgeons Grading Score for Subarachnoid Hemorrhage (WFNS) and Fisher grading (SAH graduation based on CT-scan) [16] where applicable
Model 2: 24 h weather changes (Fig. 3) There was no association between the risk of SAH and 24 h changes in all three investigated meteorological variables at all lag times except for SAH risk in patients with aneurysms that were smaller than 7 mm
Summary
Most spontaneous subarachnoid hemorrhages (SAH) occur unexpectedly and independently of classical risk factors. In the light of increasing climate variability and change, we investigated weather and rapid weather changes as possible short-term risk factors for SAH. One major disease with an incidence of approximately 9 per 100 000 person-years is spontaneous subarachnoid hemorrhage (SAH). The high mortality rate and limited interventional options render SAH a devastating disease: nearly one-third of all patients suffering from SAH do not survive the first month after initial bleeding [3] and nearly half of the survivors remain disabled after another year [4]. Supported by the observation of a seasonal variation in SAH occurrence [7], it has previously been discussed that certain weather conditions may increase the individual risk of SAH [8,9,10,11]. A recent meta-analysis even failed to pool data on a weather-associated SAH risk because determinants were too heterogeneous [12] leaving the question of an association between weather and risk of SAH unanswered
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