Lavigne Maltby Cote 2023

We extracted all ED admissions for MBD from the National Ambulatory Care Reporting System (NACRS) database administered by CIHI that occurred between March 1st, 2004 and December 31st, 2020 in 5 health regions in the province of Alberta and 35 health regions in the province of Ontario (Gibson et al., 2008). We included ED visits regardless if these resulted or not in subsequent hospital admission.

The researchers collected all emergency department visits related to mental and behavioural disorders from a national Canadian health database. These records covered patients from 5 health regions in Alberta and 35 health regions in Ontario from March 2004 to December 2020, including visits that did not lead to hospital admission.

Ambient extreme temperatures have been found to be significantly associated with total and cause-specific morbidities (Ye et al., 2012; Xu et al., 2020). A growing number of studies have also reported associations between extreme temperatures and the psychotic exacerbation of core symptoms for many mental and behavior disorders (MBDs).

Extreme hot and cold weather is strongly linked to overall illness as well as specific types of health conditions. Many studies have also shown that extreme temperatures can worsen psychotic symptoms and core symptoms of various mental and behavioural disorders.

In total, there were 9,958,759 ED visits for MBDs in Alberta and Ontario between March 1st, 2004 and December 31st, 2020. Most cases were observed in Ontario, were 30-49 years of age (33.8%) and were females (53.2%).

From March 2004 to December 2020, almost 10 million people went to the emergency department in Alberta and Ontario for mental and behavioural disorders. Most of the patients were from Ontario, were between 30 and 49 years old, and more than half of them were female.

We also found that the associations between extreme heat and MBD ED visits were stronger among those aged 30-49 years and among those with the highest level of neighborhood deprivation. Residential exposure to increasing tree canopy coverage appeared to play a beneficial role in mitigating the effect of exposure to extreme heat while higher daily levels of NO2 and O3 appeared to enhance the risk of heat on MBD ED visits.

The relationship between extreme heat and mental health emergency visits was stronger among people aged 30 to 49 and among those living in highly deprived neighbourhoods. Living near more tree canopy helped reduce the impact of heat, while higher levels of air pollution such as NO2 and O3 increased the risk of heat-related mental health emergency visits.

Future research could build on this study by expanding data collection beyond Alberta and Ontario. Although these two provinces were selected because they have a well-established and mandatory emergency department reporting system, future studies could explore alternative national data sources or develop new methods to include other provinces and territories.

I found the statistical analysis to be the most challenging part to fully understand. In particular, I had difficulty fully understanding how the distributed lag non-linear models (DLMNs) measured the delayed effects of temperature over time and how to interpret the odd ratios (ORs).