Extreme heat may increase rates of mental health ED visits

Extreme heat exposure appeared linked to higher rates of mental health-related ED visits, according to results of a case-crossover study published in JAMA Psychiatry.

“Ambient temperature has been previously associated with exacerbation of symptoms for many mental and behavioral disorders, including self-reported adverse mental health outcomes, and elevated risk for ED visits for any mental health cause, mood-anxiety disorders, substance use and schizophrenia, as well as higher suicide risk,” Amruta Nori-Sarma, PhD, MPH, of the department of environmental health at Boston University School of Public Health, and colleagues wrote. “However, existing studies have been limited by small sample sizes, specific populations or geographic areas, or reliance on self-reported mental health symptoms.

“Thus, the association between heat and mental health remains incompletely quantified, and little is known about whether certain population subgroups have increased risk factors for visiting the ED for mental health diagnoses because of exposure to higher ambient temperature,” they added.

To address this research gap, Nori-Sarma and colleagues analyzed medical claims data from a single database to pinpoint claims for ED visits with a primary or secondary discharge psychiatric diagnosis between May and September from 2010 through 2019. They included claims for adults aged 18 years and older with commercial or Medicare Advantage health insurance who lived in 2,775 U.S. counties and excluded ED visits that were for screening for mental health outcomes and impulse control disorders.

Further, they assessed the daily incidence rate of cause-specific mental health diagnoses and a composite end point and any mental health diagnosis via identification of ED visit claims according to primary and secondary discharge diagnosis ICD-9 and ICD-10 codes.

Nori-Sarma and colleagues included data from 3,496,762 ED visits among 2,243,395 unique individuals (56.8% women; mean age, 51 years), of whom 14.3% were aged 18 to 26 years, 25.6% were aged 27 to 44 years, 33.3% were aged 45 to 64 years and 26.8% were aged 65 years or older. Results showed an association between days of extreme heat and an incidence rate ratio of 1.08 (95% CI, 1.07-1.09) for ED visits for any mental health condition. Researchers noted associations between extreme and heat and ED visits for specific mental health conditions, including substance use disorders (IRR = 1.08; 95% CI, 1.07-1.1); anxiety, stress-related and somatoform disorders (IRR = 1.07; 95% CI, 1.05-1.09); mood disorders (IRR = 1.07; 95% CI, 1.05-1.09); schizophrenia, schizotypal and delusional disorders (IRR = 1.05; 95% CI, 1.03-1.07); self-harm (IRR = 1.06; 95% CI, 1.01-1.12); and childhood-onset behavioral disorders (IRR = 1.11; 95% CI, 1.05-1.18). Moreover, they found higher associations among men (IRR = 1.1; 95% CI, 1.08-1.12) and individuals in the U.S. Northeast (IRR = 1.1; 95% CO, 1.07-1.13), Midwest (IRR = 1.11; 95% CI, 1.09-1.13) and Northwest (IRR = 1.12; 95% CI, 1.03-1.21) regions.

“Results of this case-crossover study suggest that there was an association between elevated ambient temperature and ED visits for any mental health condition and for specific mental health diagnoses,” Nori-Sarma and colleagues wrote. “This finding could aid clinicians who provide mental health services in preparing for increases in health service needs when high ambient temperature is anticipated. Further research could investigate the implications of sustained periods of extreme heat (heat waves) for health outcomes and continue to investigate the association among different populations.”

In a related editorial, Nick Obradovich, PhD, of the Max Planck Institute for Human Development in Germany, and Kelton Minor, MS, of the Copenhagen Center for Social Data Science at the University of Copenhagen in Denmark, connected these study results to climate change as a whole.

“Thus far, the collective scientific and clinical knowledge is sparse relative to the specter of the coming threat climate change poses to human mental health,” they wrote. “Ever-more mental health scientists and clinicians are needed to work on this topic. It is not overwrought to say it: humanity needs your help. As bad as certain climatic stressors already are, this truly is just the beginning.”

Reference:

• Obradovich N, Minor K. JAMA Psychiatry. 2022;doi:10.1001/jamapsychiatry.2021.4280.