Abstract TP210: Short-Term Changes in Ambient Temperature and Risk of Ischemic Stroke Onset
Background: Despite consistent evidence of a higher short-term risk of cardiovascular mortality associated with ambient temperature, there have been discrepant findings on the association between temperature and ischemic stroke hospitalization. Moreover, few prior studies have considered potential confounding by ambient fine particulate matter air pollution <2.5 μm in diameter (PM2.5).
Methods: We reviewed the medical records of 1,705 Boston area patients hospitalized with neurologist-confirmed ischemic stroke and abstracted data on the time of symptom onset and clinical characteristics. We obtained hourly meteorological data from the National Weather Service station at Boston’s Logan airport and calculated mean apparent temperature as an index of perceived discomfort due to heat and humidity. Hourly PM2.5 was obtained from the Harvard ambient monitoring station. We used the time-stratified case-crossover study design to assess the association between the risk of ischemic stroke onset and apparent temperature in the hours and days preceding each event, after accounting for PM2.5, patient characteristics, season, and long-term time trends.
Results: We found a 20% (95% confidence interval 3% to 33%) higher risk of ischemic stroke associated with a 100C decrease in mean apparent temperature in the 4 days preceding symptom onset. The higher risk associated with cooler temperatures was observed within 14 to 24 hours. Results were similar in analyses stratified by season.
Conclusions: Lower temperatures are associated with a higher risk of ischemic stroke onset in both warm and cool seasons. Additional work is necessary to examine the potential mechanisms underlying these observations and to examine whether other environmental factors may account for this association.
- © 2012 by American Heart Association, Inc.