Acute impacts of extreme temperature exposure on emergency room admissions related to mental and behavior disorders in Toronto, Canada

Background: The purpose of this study was to assess the effects of extreme ambient temperature on hospital emergency room visits (ER) related to mental and behavioral illnesses in Toronto, Canada. Methods: A time series study was conducted using health and climatic data from 2002 to 2010 in Toronto, Canada. Relative risks (RRs) for increases in emergency room (ER) visits were estimated for specific mental and behavioral diseases (MBD) after exposure to hot and cold temperatures while using the 50th percentile of the daily mean temperature as reference. Poisson regression models using a distributed lag non-linear model (DLNM) were used. We adjusted for the effects of seasonality, humidity, day-of-the-week and outdoor air pollutants. Results: We found a strong association between MBD ER visits and mean daily temperature at 28 degrees C. The association was strongest within a period of 0-4 days for exposure to hot temperatures. A 29% (RR= 1.29, 95% CI 1.09-1.53) increase in MBD ER vists was observed over a cumulative period of 7 days after exposure to high ambient temperature (99th percentile vs. 50th percentile). Similar associations were reported for schizophrenia, mood, and neurotic disorers. No significant associations with cold temperatures were reported. Limitations: The ecological nature and the fact that only one city was investigated. Conclusions: Our findings suggest that extreme temperature poses a risk to the health and wellbeing for individuals with mental and behavior illnesses. Patient management and education may need to be improved as extreme temperatures may become more prevalent with climate change. (C) 2013 Elsevier B.V. All rights reserved.