Heat Extremes and Suicide

Suicide is among the most pressing of public health concerns. Increased ambient temperatures (e.g., excess heat) has been repeatedly linked to increased suicide rates, however, we still know little about the mechanisms underlying this relationship. Adults with mental illness and substance use disorders are at an elevated risk for heat-related mortality. Whether or not individuals with mental illness or substance use disorders are at increased susceptibility for temperature-associated suicide is unclear. We propose to use claims data from the two largest insuring bodies in the United States (Medicare and Medicaid) linked to death certificate data and climate data to model the temperature-suicide connection at unprecedented depth. Using a self-controlled case series approach, incident rate ratios for suicide death and emergency services utilization for suicidal ideation, behaviors, and non-lethal attempts following exposure to excess heat events will be calculated. Unsupervised clustering of year prior to death sociodemographic, healthcare utilization, medical and mental health diagnosis, and medication prescription characteristics of those who die by suicide following a excess heat event will be used to identify temperature-associated suicide phenotypes. Finally, using social media-derived suicide narratives, topic modeling will help to determine recurrent themes associated to mentions of increased heat and other climate-related phenomena (e.g., droughts, wildfires). Excess heat is a climate change-associated event that is experienced by the most individuals annually. At the current rate of warming, global temperatures are expected to increase by 1.5 degrees Celsius by 2052. Given an existing upward trend in suicide rate in US, even a slight increase in suicide rate due to increased warming could prove devastating.