New Insights into Weather and Stroke: Influences of Specific Air Masses and Temperature Changes on Stroke Incidence

Abstract

Background/Objectives: Meteorological factors seem to influence stroke incidence, however, the complex association between weather and stroke remains unclear. Possible explanations from the literature do not categorize into subdivisions of ischemic strokes, only have small patient numbers, or refer to a selection of isolated weather elements without investigating weather changes and more. Method: In this exploratory trial, almost 18,000 stroke cases from a single stroke center in Southern Germany were analyzed from 2006 to 2015 and classified into the main subgroups of strokes and subdivisions of ischemic stroke etiologies applying the Trial of Org 10172 in Acute Stroke Treatment classification. For each stroke event, the air mass classification was determined from a subset of 7 air mass categories. Relative excess morbidities were derived for the 7 different air mass categories, taking into account the day of the event and up to 2 and 5 days preceding the stroke event. Results: Statistically significant findings (α ≤0.1) reveal that dry tropical air masses were associated with a lower/higher risk for hemorrhagic (HEM)/macroangiopathic strokes (MAS), respectively. Dry polar air masses were associated with a higher risk for intracerebral bleedings and lower risk for ischemic stroke subtypes. Moist air masses were associated with a reduced incidence of MAS. A strong temperature increase 5 days prior to the event was associated with a lower risk of HEM strokes. Temperature increases were associated with lower risks for MAS and cardio-embolic strokes. Significant temperature decreases were associated with a higher risk of MAS. Conclusions: Temperature effects were dependent on both air masses and temperature changes within 5 days prior to the event and were associated with statistically relevant changes in stroke incidence. Decisive factors such as etiology, age, sex, and risk factors were also taken into account.

Machine Learning Models Predicting Incidence, Severity, and Early Outcomes of Hemorrhagic Stroke from Weather Parameters and Individual Risk Factors

“…From the results obtained, the atmospheric factors that predict HS with highest accuracy were not absolute values of humidex, WS, AP, and temperature but their monthly changes. These results were consistent with previous statistical analysis (31) and justified the use of a distributed lag nonlinear model in this study. Furthermore, we demonstrated that HS incidence is affected by air masses, i.e.…”

“…Exposure to cold temperatures can disrupt normal homeostatic mechanisms and increase heart rate, blood pressure, platelet count, blood viscosity, serum low-density lipoprotein-cholesterol concentration, and other cardiac biomarkers, thereby elevating cardiovascular event risk (37,38). We showed the adverse effect of low temperatures on ICH incidence, which is consistent with the findings of several previous studies (18,20,31,39,40,41,42,43). However, lower or unchanged HS risk was also reported (44).…”

“…One of them reported an increased risk of intracerebral bleeding when dry polar air masses appeared, and a reduced HS risk 5-days later. This suggests that the delayed effects on stroke incidence are dependent on the cumulative effects of air masses and temperature changes (31). Novel studies should overcome recent research limitations by texting the entire range of relevant individual risks and weather elements.…”

Dependence of seasonal dynamics of hemorrhagic and ischemic strokes on the climate of a region: A meta-analysis

“…Most of these regions are characterized by hot summers, and many authors associate IS risk with hot weather. 2,5,47,48 However, in other regions with hot summers, but without strong seasonal fluctuations in atmospheric pressure, for example, in Italy, Croatia and Greece, IS were more common in winter than in summer. 19,22,25,30,34 Also, studies in Novosibirsk have shown an increase in IS in winter.…”

Prognostication of Incidence and Severity of Ischemic Stroke in Hot Dry Climate From Environmental and Non-Environmental Predictors

“…A later study justified an effect of age, sex, and smoking status on the IS morbidity [34]. Some scientists analysed changes in the air masses due to the wind and justified that dry polar air was associated with a lower IS risk [35]. Further studies are required to get an insight if the weather parameters interact with individual risk factors to influence the IS incidence in distinct geographic locations.…”