• Chia-Chun Tai, Chien-Chang Lee, Chung-Liang Shih, and Shyr-Chyr Chen.
• Department of Emergency Medicine, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan.
• Emerg Med J. 2007 Sep 1; 24 (9): 641-4.

AimTo evaluate the effects of change of ambient temperature on emergency department (ED) patient visits.MethodsThis prospective observational study was conducted in the ED of National Taiwan University Hospital from January 2002 to January 2007. The daily ED patient numbers of different triage levels in different service specialties were collected and correlated with the daily average temperature (T) and change in temperature (deltaT) compared with the previous day. A univariate analysis was performed with the Pearson correlation and a multivariate analysis with multiple linear regression analysis.ResultsA total of 505,224 patient visits were included in this study. On univariate analysis, there was no significant correlation between T and the ED volume (r = 0.012, p = 0.608), but there was a significant correlation between deltaT and ED volume (r = 0.109, p<0.001). On multivariate analysis, deltaT and holidays were identified as independent predictors of ED volume. We established the following formula in predicting the ED patient number: y = 265.42 + (0.06 x T) + (2.57 x deltaT) + (59.77 x holiday). There was a positive association between T and the trauma patient number, while there was a negative association between T and medical and paediatric patient numbers. On the triage level, a low T was associated with increased patient triage level, while no significant association was noted between deltaT and the proportion in any triage level.ConclusionsOur study demonstrated that ambient temperature had differential effects on ED patient visits of different specialties and severities.

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