A High-Resolution Analysis on the Meteorological Influences on Spontaneous Intracerebral Hemorrhage Incidence

Daily Meteorological Parameters Influence the Risk of Intracerebral Hemorrhage in a Subtropical Monsoon Basin Climate

Background and Purpose

The correlation between meteorological parameters and intracerebral hemorrhage (ICH) occurrence is controversial. Our research explored the effect of daily meteorological parameters on ICH risk in a subtropical monsoon basin climate.

Methods

We retrospectively analyzed patients with ICH in a teaching hospital. Daily meteorological parameters including temperature (TEM), atmospheric pressure (PRE), relative humidity (RHU), and sunshine duration (SSD) were collected, with the diurnal variation (daily maximum minus minimum) and day-to-day variation (average of the day minus the previous day) calculated to represent their fluctuation. We adopted a time-stratified case-crossover approach and selected conditional logistic regression to explore the effect of meteorological parameters on ICH risk. The influence of monthly mean temperature proceeded via stratified analysis. Air pollutants were gathered as covariates.

Results

Our study included 1052 eligible cases with ICH. In a single-factor model, the risk of ICH decreased by 5.9% (P<0.001) for each 1°C higher of the daily mean TEM, and the risk increased by 2.4% (P=0.002) for each 1hPa higher of the daily mean PRE. Prolongation of daily SSD inhibited the risk of ICH, and OR was 0.959 (P=0.007). The risk was raised by 7.5% (P=0.0496) with a 1°C increment of day-to-day variation of TEM. In a two-factor model, the effect of daily mean TEM or daily SSD on ICH risk was still statistically significant after adjusting another factor. The influence of meteorological parameters on ICH risk continued in cold months but disappeared in warm months after stratified analysis.

Conclusion

This research indicates daily TEM and SSD had an inverse correlation to ICH risk in a subtropical monsoon basin climate. They were independent when adjusted by another factor. Daily PRE and day-to-day TEM variation were positively related to ICH risk. The correlation of daily meteorological factors on ICH risk was affected by the monthly thermal background.

Effects of cold temperature and snowfall on stroke mortality: A case-crossover analysis

BACKGROUND

We sought to determine if cold temperature and snowfall are independently associated with stroke mortality, and whether effects differ between hemorrhagic and ischemic stroke.

MATERIALS AND METHODS

We conducted a case-crossover study of 13,201 stroke deaths utilizing weather records between the months of November and April for Quebec, Canada from 1981 to 2015. We compared exposure to cold temperature and snowfall with controls days when stroke death did not occur. We computed odds ratios (OR) and 95% confidence intervals (CI) for the association of minimum temperature and duration of snowfall with stroke, adjusted for change in barometric pressure and relative humidity.

RESULTS

The likelihood of mortality the day following exposure to cold temperature was elevated for hemorrhagic stroke in men, independent of snowfall. Relative to 0 °C, a temperature of -20 °C was associated with 1.17 times the odds of hemorrhagic stroke death (95% CI 1.04-1.32). An independent effect of snowfall was also present in men, with 12 h of snowfall associated with 1.12 times the odds of hemorrhagic stroke death (95% CI 1.00-1.24) compared with no snowfall. There was no evidence of an increased risk in women. Cold temperature and snowfall were not associated with ischemic stroke death in either men or women.

CONCLUSION

Our results suggest that cold temperature and snowfall are independent risk factors for death from hemorrhagic stroke in men. These findings imply that interventions to prevent fatal hemorrhagic stroke during winter should include both cold temperature exposure and snowfall in men.

Hypertension modifies the short-term effects of temperature on morbidity of hemorrhagic stroke

BACKGROUND

This study estimated the effects of ambient temperature on hospital admissions for hemorrhagic stroke during 2004-2009 in Jinan, China, and the effect modification of hypertension status.

METHODS

The exposure-response relationship between temperature and hemorrhagic stroke was firstly examined, and then the association between daily mean temperature and hemorrhagic stroke was investigated using a generalized additive model. Stratified analyses were conducted to examine the potential effect modification of hypertension.

RESULTS

A total of 1577 hemorrhagic stroke cases were observed between 2004 and 2009, among which, 1058 were hypertensive and 519 were non-hypertensive. We found an approximately linear relationship between ambient temperature and hemorrhagic stroke. Each 1°C decrease in the current day's temperature was associated with 1.63% (95% CI: 0.33%, 2.95%) increase in daily hemorrhagic stroke. The stratified analyses observed that the association was significant among hypertensive hemorrhagic stroke, each 1°C decrease in the current day's temperature was associated with 2.26% (95% CI: 0.57%, 3.98%) increase in daily hypertensive hemorrhagic stroke. While no significant effect was observed for non-hypertensive hemorrhagic stroke.

CONCLUSIONS

Low temperature might be one risk factor for hemorrhagic stroke and hypertension may be one effect modifier of this association in Jinan, China.