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Abstract: Background: Most research on the seasonality of acute coronary syndrome (ACS) has been were reported from hospital-based data. We aimed to investigate the seasonal distribution of ACS in Beijing and to elucidate the relations between ACS occurrence and climatic parameters in a prehospital setting. Methods: We retrospectively reviewed the electronic prehospital medical records from the Beijing''s emergency medical service system spanning August 1, 2005, to July 31, 2007. Case data were analyzed by month and season with χ 2 test. The effects of climatic factors on the occurrence of ACS were analyzed by Poisson regression with generalized linear model. Results: During the 2-year study period, a total of 7037 ACS events were identified, including 4135 male patients (58.8%) and 2902 female patients (41.2%). Significant variations were observed in the monthly (P < .001) and seasonal (P < .001) distribution of ACS. The highest seasonal incidence occurred in winter and lowest in autumn. Significant negative correlations were noticed between the number of ACS events and daily mean temperature (P < .001) and between the number of ACS events and barometric pressure (P < .001). Comparing to the baseline level (temperature of 25°C to approximately 31°C; barometric pressure of 1026 to approximately 1048 hectopascal (hPa)), an increase of 41.3% of daily ACS incidence was associated with temperature lower than 2°C (−10.0°C to approximately 2.0°C), and an increase of 19.8% was associated with barometric pressure under 1006 hPa (991.0 to approximately 1006 hPa). Conclusions: There are clear monthly and seasonal rhythms of ACS in Beijing metropolitan area. Temperature and barometric pressure are negatively related with the occurrence of ACS. [Copyright &y& Elsevier]

Background: Many studies have identified strong correlations between winter months and acute, unintentional carbon monoxide (CO) poisoning. In this study, we aimed to investigate the incidence pattern of acute domicile-related CO poisoning in Beijing and its relation with climatic factors. Methods: Data on CO poisoning were collected from the emergency medical service system during August 1, 2005, to July 31, 2007, in Beijing. Variations of the monthly and seasonal distribution of CO poisoning occurrences were examined with χ 2 testing. Climatic data including temperature, barometric pressure, humidity, wind speed, and visibility were obtained from the Beijing Meteorological Bureau. Correlations between the occurrence of CO poisoning and mean of each meteorological parameter spanning 3 days were analyzed with partial correlation test, with related parameters controlled. Results: Significant differences were found among the cases occurring each month of the year (P < .001). The monthly caseload reached the peak and the nadir in January and in September, respectively. During the cold period, 3331 patients were recorded, accounting for 88.4% of the total cases of the 2-year study period. Among the 5 climatic parameters, only temperature had a significant inverse correlation with the occurrence of CO poisoning (P < .001, r = –0.467). Conclusions: The incidences of CO poisoning were highest during winter, particularly during the time period when charcoal or coal use for indoor heating would be most prevalent in Beijing. [Copyright &y& Elsevier]

Abstract: Background: Previous in-hospital studies suggest that there are significant circadian rhythms associated with the incidence of acute coronary syndromes (ACSs). No study to date has examined the presentation of ACS in the prehospital setting. Our goal was to examine circadian, day-of-week, and age patterns of occurrence in ACS in a large, urban emergency medical services (EMS) system. Methods: We retrospectively reviewed the electronic prehospital medical records from the Beijing''s EMS system spanning August 1, 2005, to July 31, 2007. Data were analyzed by hour of the day and day of the week. χ 2 tests were performed to compare the difference. Results: Seven thousand thirty-two cases of ACS were identified by the EMS system physicians during the 2-year study period, including 536 cases of acute myocardial infarction. A significant variation of circadian distribution of ACS was observed in both 24-hour (P < .001) and 2-hour (P < .001) interval time course. Two peaks were observed in the morning from 0800 to 1000 and approaching midnight from 2200 to 2400. Increases of 50% and 60.8% in the morning and evening peaks were found, respectively, when compared with the early morning baseline (nadir). No significant difference was found among the accumulated cases in 2 years on each day in a week (P = .203). Conclusions: Our study shows that, in the Beijing metropolitan area, the presentation of ACS has significant circadian rhythm characterized by 2 peaks within 24 hours, the morning peak is 0800 to 1000, and the late evening peak is 2200 to 2400. No significant weekly rhythm was observed in the present study. [Copyright &y& Elsevier]