The Impact of Surges on Hospital COVID-19 Mortality Rates

Abstract

Background: Hospital mortality rates among COVID-19 admissions fell as early surges waned, critical supply shortages were addressed, and new treatment options became available. However, new surges in late 2020 provide an opportunity to understand whether and how regional COVID-19 surges might overwhelm hospital systems in ways that impact the survivability of the disease among admitted patients. Methods: Electronic health records representing all COVID-19 inpatient admissions from 52 hospitals in the western US between May 2020 and February 2021 were analyzed. Multilevel logistic regression was used to assess the relationship between COVID-19 surges (defined as the percent of a hospital’s total bed capacity occupied with COVID-19 patients) and in-hospital mortality among COVID-19 patients while adjusting for patient demographics, comorbidities, severity of illness at admission, and major treatment strategies. Participants included any patient admitted to a participating hospital with a lab-confirmed COVID-19 diagnosis between May 1, 2020 and February 28, 2021 (n=34,683 distinct admissions). Findings: Mortality rates for COVID-19 admissions went up when hospitals were filled with more COVID-19 patients. Holding constant the effects of patient characteristics, comorbidities, major treatments, and severity of illness at admission, a 5% increase in the proportion of hospital beds occupied by COVID-19 patients was associated with a 10% (OR=1.10, pInterpretation: Results suggest that “surge effects” are a significant driver of hospital mortality, even in the absence of the critical supply shortages and uncertainty about treatment options that characterized the early pandemic. Results were not driven by “enriched” risk among admitted patients during surge periods. Rather, hospital systems overwhelmed with large volumes of COVID-19 patients may face barriers to optimal care delivery that result in a higher mortality rate among admitted patients. Preventing COVID-19 surges may help decrease not just the number of deaths, but the rate of deaths as well. Funding: The authors received no special funding for this study.Declaration of Interests: None to declare. Ethics Approval Statement: This study was approved by PSJH IRB with number: STUDY2021000078