The Relationship Between Climatic, Meteorological Conditions And Environmental Parameters And Stroke Occurrence

Part I: The Relationship between Climatic and Meteorological Conditions andHemorrhagic Stroke Occurrence:Epidemiological StudyObjectives:Previous studies have shown associations between intracerebral hemorrhage(ICH) and meteorological conditions, but their conclusions have been inconsistent. The aim of the study was to analyze and discuss the relationship between daily meteorological parameters and daily as well as seasonal ICH incidence.Methods:We collected medical information of consecutive patients whose first diagnosis was ICH registered in our hospital from 1 January 2012 to 31 December 2014. We assessed the relationship between daily ICH occurrence and daily meteorological factors including temperature, humidity, atmospheric pressure, wind direction and rainfall. The distribution of onset time of ICH in 24 hours was also analyzed. The χ2 test for goodness of fit was used for statistical evaluations.Results:1. Among all of the ICH patients, the value of male was more than female and the mean age of female(64.17±15.75)was higher than male(62.27±15.09)(p<0.001).2. The incidence of ICH had statistically significant seasonal patterns: the value of ICH patients was most during winter and fewest during summer. The value of ICH patients was most during January and fewest during September.3. The incidence of ICH had statistically significant diurnal patterns : the time of onset for all ICH patients or the elderly(age >60y) was most common between 4:00 AM and 8:00 AM, while for the younger(age ≤45y) it was between 16:00 PM and 20:00 PM.4. The relation between the occurrence of ICH and weekly variations was not found.5. We found that daily mean temperature, daily minimum temperature and daily maximum temperature had negative correlation with the hospitalizations of ICH, but daily mean atmospheric pressure had positive correlation with the hospitalizations of ICH. No statistically significant relation was observed between daily mean humidity and ICH onset, neither for the daily rainfall.6. Daily major wind direction had associations with the onset of ICH: when it was southeast wind, the value of ICH was most; when it was southwest wind, the value of ICH was fewest; when it was north wind, the risk of ICH onset was highest.Conclusions:1. Our study demonstrated that distinct patterns of seasonal and monthly variationsin the incidence of ICH: the value of ICH onset was highest during winter andcold months, but it was fewest during summer.2. The onset of ICH had an increasing trend when the temperature dropped or the airpressure rose; the old people need to pay more attention to keeping warm from thecold to reduce the risk of ICH.3. More attention was required to be paid to the risk of ICH onset after waking in oldpeople.Part II:Effect of Short-term Exposure of Atmospheric Particulates on StrokeOccurrence:Meta-analysis and Systematic Review AbstractObjective : To investigate the impact of short-term exposure of atmospheric particulates(PM10/PM2.5) on admission to hospital from stroke.Methods:Based on the online search of studies published from 1 January 1990 to 31 December 2014, 37 satisfied our inclusion criteria and were included in meta analysis. The presented odds ratio, adjusted per 10 ug/m~3 increase in particulate matters, was combined with fixed or random effect model according to the heterogeneity. We also did sensitivity and subgroup analysis.Results:Stroke hospitalizations increased 0.8%(95%CI: 0.4–1.2) per 10 μg/m~3 increase in PM10, 1.4%(95%CI: 0.6–2.2) per 10 μg/m~3 increase in PM2.5. Publication bias existed in studies on PM10, not PM2.5. Sensitivity analysis showed that the results for both PM10 and PM2.5 were not robust. In the subgroup analysis, we found that the short-term exposure to PM10 was associated with ischemic not hemorrhagic stroke, whereas, positive associations were found significant for ischemic or hemorrhagic stroke in studies on PM2.5. Besides, the results according to different study design showed that case-crossover study had higher risk estimates than time-series study.Conclusions : Short-term increase of concentrations of PM10 and PM2.5 was positively associated with increase of stroke hospitalizations; PM2.5 played a higher risk contribution than PM10; PM2.5 and PM10 may have different effects on different stroke subtypes.