Excess mortality in the Colorado Front Range during the COVID-19 pandemic and a concurrent intense wildfire season

Abstract

BACKGROUND AND AIM: COVID-19 has had a substantial public health impact in the United States. In the western US, the pandemic has coincided with some of the worst wildfires in history. The current analysis aimed to estimate excess mortality in the Front Range region of Colorado during the convergent disasters of the COVID-19 pandemic and an intense wildfire season. METHODS: We obtained weekly death counts from 2010-2020 for the study area from the state's vital statistics program. We modeled all-cause mortality and deaths due to cardiovascular, respiratory or kidney disease, cancer, diabetes, deaths of despair (suicide and overdose), and other causes. To estimate excess deaths, we fit quasipoisson generalized additive models for each cause with a smoothing term for week to account for temporal trends using data from January 2010 through the first week in March (prior to the first case of COVID-19 in the state). We then predicted expected deaths from the second week in March through December 2020. We defined excess deaths as the difference between the observed count and the upper limit of the 95% prediction interval for each week. RESULTS:In 2020, we estimated 3740 excess deaths, which exceeded the observed number of COVID-19 deaths (n = 3159). Most excess deaths occurred at the beginning of the pandemic (March-April) and from October through December. When examining specific causes, the timing of excess deaths varied. Excess cardiovascular disease deaths (n = 257) occurred throughout the pandemic. Excess deaths of despair (n = 103) peaked in July and August. CONCLUSIONS:Our results suggest there may be important environmental factors contributing to excess deaths during the pandemic. We hypothesize that some excess deaths may be attributable to pandemic lockdown policies or exposure to high temperatures or wildfire smoke. Future work will further examine the confluence of heat, wildfires, and COVID-19 on mortality risk in Colorado. KEYWORDS: COVID-19, wildfires, socioeconomic factors, mortality