The influence of temperature and humidity on Emergency Department syncope attendances

The objective of this study was to assess whether the number of syncope attendances to the Emergency Department is related to daily temperature and humidity, or time of the day, day of the week, month or season of the year. All adult patients presenting with syncope over a 1-year period between 1 March 2007 and 29 February 2008 were enrolled. A circadian pattern of syncope attendances exists, peak attendance was between 10:00 and 16:00h, especially in those aged above 65 years (P<0.001). There was no obvious relationship between attendances and mean daily temperature (r=0.16) and attendances and mean daily humidity (r=-0.14). There were 11% more attendances between December and May than between June and October (P=0.8, NS, χ). In Conclusion, there is a circadian pattern of syncope attendances to the Emergency Department. The peak time for presentations is between 10:00 and 16:00h. A trend was found towards more attendances between December and May. One hypothesis for this is differences between indoor and outdoor temperatures. Public health campaigns could be targeted towards elderly patients to ensure that they are aware of the increased risk of syncope on waking and also on transferring from cold to warm environments.