Hospital-Level Variation in Death for Critically Ill Patients with COVID-19

Am J Respir Crit Care Med. 2021 Aug 15;204(403-411):403-411. doi: 10.1164/rccm.202012-4547OC.


Rationale: Variation in hospital mortality has been described for coronavirus disease 2019 (COVID-19), but the factors that explain these differences remain unclear.

Objective: Our objective was to utilize a large, nationally representative dataset of critically ill adults with COVID-19 to determine which factors explain mortality variability.

Methods: In this multicenter cohort study, we examined adults hospitalized in intensive care units with COVID-19 at 70 United States hospitals between March and June 2020. The primary outcome was 28-day mortality. We examined patient-level and hospital-level variables. Mixed-effects logistic regression was used to identify factors associated with interhospital variation. The median odds ratio (OR) was calculated to compare outcomes in higher- vs. lower-mortality hospitals. A gradient boosted machine algorithm was developed for individual-level mortality models.

Measurements and main results: A total of 4,019 patients were included, 1537 (38%) of whom died by 28 days. Mortality varied considerably across hospitals (0-82%). After adjustment for patient- and hospital-level domains, interhospital variation was attenuated (OR decline from 2.06 [95% CI, 1.73-2.37] to 1.22 [95% CI, 1.00-1.38]), with the greatest changes occurring with adjustment for acute physiology, socioeconomic status, and strain. For individual patients, the relative contribution of each domain to mortality risk was: acute physiology (49%), demographics and comorbidities (20%), socioeconomic status (12%), strain (9%), hospital quality (8%), and treatments (3%).

Conclusion: There is considerable interhospital variation in mortality for critically ill patients with COVID-19, which is mostly explained by hospital-level socioeconomic status, strain, and acute physiologic differences. Individual mortality is driven mostly by patient-level factors. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (

Keywords: COVID-19; Critical Care; Health Disparities; Intensive Care Unit.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Algorithms*
  • COVID-19 / epidemiology*
  • Comorbidity
  • Critical Illness / epidemiology
  • Critical Illness / therapy*
  • Female
  • Follow-Up Studies
  • Hospital Mortality / trends
  • Humans
  • Incidence
  • Intensive Care Units / statistics & numerical data*
  • Male
  • Middle Aged
  • Prognosis
  • Retrospective Studies
  • Risk Factors
  • SARS-CoV-2
  • Survival Rate / trends
  • United States / epidemiology