The 2019 Getty Fire and healthcare visits among vulnerable older adults in Southern California

Abstract

Introduction: Prior wildfire studies have relied on hospital claims data to evaluate associations between wildfire-related particulate matter (PM2.5) and acute cardiovascular and respiratory outcomes, but have not assessed dementia-related visits. Here, we focus on the 2019 Getty Fire in Southern California and evaluate both wildfire-related PM2.5 and evacuation-related exposures and acute and chronic healthcare visits among Kaiser Permanente Southern California (KPSC) members who rely on at-home electricity-dependent medical equipment (DME) or that had a prior dementia diagnosis. Methods: We estimated PM2.5 exposures in a two-stage approach: we first estimated total PM2.5 levels and we subsequently used NOAA’s Hazard Mapping System to identify ZIP codes exposed to wildfire smoke plumes. We use the smoke plume information combined with multiple imputation to estimate daily wildfire PM2.5 and non-wildfire PM2.5 levels. Areas required to evacuate or under evacuation watch were identified from local media sources and linked to patient address. We used case-crossover and difference-in-differences designs to estimate associations between wildfire exposures and acute healthcare utilization among two vulnerable KPSC populations.Results: The Getty Fire ignited on October 28, 2019, burned until November 5, 2019, resulted in daily-average PM2.5 levels >25g/m3, and caused 25,000 people to evacuate. While overall KPSC visits decreased during the Getty Fire (-9%), dementia patients living in ZIP codes 20-km from the Getty boundary had a 20% increase in overall, as well as in dementia-related visits, compared to ZIP codes located >20-km away during the same period. Among patients with a prior dementia diagnosis, we found outpatient and ED visits declined by 10% among those living in ZIP codes with mandatory evacuation compared to ZIP codes located >20-km away.Discussion: These findings highlight the need to consider longer relevant time periods and evacuation exposures, which may limit access to healthcare altogether.