Objective To investigate the quarterly , monthly and daily distribution of the cases of acute onset of cerebrovascular diseases , and explore the influence of meteorological factors on the acute onset of cerebrovascular diseases.Methods We collected pre-hospital medical records of 8 886 patients who received pre -hospital care after calling Beijing Emergency Medical Center and were diagnosed as acute cerebrovascular diseases from January 2006 to December 2010.We also collected the meterological data of Beijing from Beijing Meterological Bureau in the same period .The quarterly, monthly and daily distributions of the cases of acute onset of cerebrovascular diseases were analyzed .The case-crossover design with time -stratification was employed to investigate the influence of meterological factors on the acute onset of cerebrovascular diseases.Results (1) The number of cases was higher in winter and spring than that in summer and autumn .The months with higher prevalence ( lowest in January and second lowest in November ) and months with lower prevalence ( lowest in September and second lowest in June ) form the shape of two peaks .Daily distribution was evidently regular , with 8: 00~10: 00 as the peak time and 22: 00 ~7: 00 as the bottom time. ( 2 ) Different seasons were significantly different ( P<0.05 ) in lowest temperature, highest temperature, average temperature, relative humidity, extreme wind speed, average wind speed and daily range; no significant differences ( P>0.05) were found in average sea -level pressure , daily change of low temperature , daily change of high temperature , daily change of average temperature and change of daily range . ( 3 ) The COX regression analysis showed the following results: in spring, highest temperature ( retardation time is one day ), average sea -level pressure (retardation time is one day) and average wind speed (retardation time is three days) had significant influence (P<0.05) on the acute onset of cerebrovascular diseases; in summer, the daily change of average temperature had significant influence (P<0.05) on the acute onset of cerebrovascular diseases; in autumn, lowest temperature and average sea -level pressure (retardation time is three days) had significant influence (P<0.05) on the acute onset of cerebrovascular diseases; in winter, average wind speed ( retardation time is three days ) , change of daily range and daily change of high temperature had significant influence (P<0.05) on the acute onset of cerebrovascular diseases .Gonclusion The quarterly and monthly distribution and daily change of the acute onset of cerebrovascular diseases are in a regular pattern .In spring, the highest temperature , average sea-level pressure and average wind speed are the influencing factors; in summer , daily change of average temperature is the influencing factor; in autumn, lowest temperature and average sea -level pressure are the influencing factors; in winter, average wind speed , change of daily range and daily change of high temperature are the influencing factors .Hysteresis effect exists in the influence of meterological factors on acute onset of cerebrovascular diseases , and the retardation time varies with different meterological factors.%目的：了解脑血管疾病急性发病例数的季、月、日分布情况，并探讨气象因素对脑血管疾病急性发病的影响。方法收集2006年1月—2010年12月，北京急救中心经120电话出诊院前急救且被诊断为急性脑血管疾病的院前急救病历8886份，以及同时期北京观象台观测的北京市气象资料。分析脑血管疾病急性发病例数的季、月、日分布情况；采用时间分层的病例交叉设计，探讨气象因素对脑血管疾病急性发病的影响。结果（1）脑血管疾病急性发病例数冬、春季高于夏、秋季；高发月（1月最高，11月次之）和低发月（9月最低，6月次之）均呈双峰单月型分布；日变化有明显的昼夜规律，8：00～10：00为高发期，22：00～次日7：00为低发期。（2）不同季节最低气温、最高气温、平均气温、相对湿度、极大风速及平均风速及日较差比较，差异有统计学意义（ P＜0.05）；平均海平面气压、低温日变化、高温日变化、平均气温日变化及日较差变化比较，差异无统计学意义（ P＞0.05）。（3） COX回归分析显示：春季，最高气温（滞后时间为1 d）、平均海平面气压（滞后时间为1 d）及平均风速（滞后时间为3 d）对脑血管疾病急性发病的影响有统计学意义（P＜0.05）；夏季，平均气温日变化对脑血管疾病急性发病的影响有统计学意义（ P＜0.05）；秋季，最低气温和平均海平面气压（滞后时间为3 d）对脑血管疾病急性发病的影响有统计学意义（P＜0.05）；冬季，平均风速（滞后时间为3 d）、高温日变化及日较差变化对脑血管疾病急性发病的影响有统计学意义（P＜0.05）。结论脑血管疾病急性发病存在季节性、月分布、日变化规律。不同季节气象因素对脑血管疾病急性发病的影响不同：春季，最高气温、平均海平面气压及平均风速是其影响因素；夏季，平均气温日变化是其影响因素；秋季，最低气温和平均海平面气压是其影响因素；冬季，平均风速、日较差变化及高温日变化是其影响因素。气象因素对脑血管疾病急性发病的影响存在一定滞后效应，且不同气象因素的滞后效应时间不同。
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