by
Sameer S Kadri;
Junfeng Sun;
Alexander Lawandi;
Jeffrey R Strich;
Lindsay Busch;
Michael Keller;
Ahmed Babiker;
Christina Yek;
Seidu Malik;
Janell Krack;
John P Dekker;
Alicen B Spaulding;
Emily Ricotta;
John H Powers;
Chanu Rhee;
Michael Klompas;
Janhavi Athale;
Tegan K Boehmer;
Adi Gundlapalli;
William Bentley;
Sriparna Datta;
Robert L Danner;
Cumhur Y Demirkale;
Sarah Warner
Background: Several U.S. hospitals had surges in COVID-19 caseload, but their effect on COVID-19 survival rates remains unclear, especially independent of temporal changes in survival. Objective: To determine the association between hospitals' severity-weighted COVID-19 caseload and COVID-19 mortality risk and identify effect modifiers of this relationship. Design: Retrospective cohort study. (ClinicalTrials.gov: NCT04688372) Setting: 558 U.S. hospitals in the Premier Healthcare Database. Participants: Adult COVID-19-coded inpatients admitted from March to August 2020 with discharge dispositions by October 2020. Measurements: Each hospital-month was stratified by percentile rank on a surge index (a severity-weighted measure of COVID-19 caseload relative to pre-COVID-19 bed capacity). The effect of surge index on risk-adjusted odds ratio (aOR) of in-hospital mortality or discharge to hospice was calculated using hierarchical modeling; interaction by surge attributes was assessed. Results: Of 144116 inpatients with COVID-19 at 558 U.S. hospitals, 78144 (54.2%) were admitted to hospitals in the top surge index decile. Overall, 25344 (17.6%) died; crude COVID- 19 mortality decreased over time across all surge index strata. However, compared with nonsurging (<50th surge index percentile) hospital-months, aORs in the 50th to 75th, 75th to 90th, 90th to 95th, 95th to 99th, and greater than 99th percentiles were 1.11 (95% CI, 1.01 to 1.23), 1.24 (CI, 1.12 to 1.38), 1.42 (CI, 1.27 to 1.60), 1.59 (CI, 1.41 to 1.80), and 2.00 (CI, 1.69 to 2.38), respectively. The surge index was associated with mortality across ward, intensive care unit, and intubated patients. The surge-mortality relationship was stronger in June to August than in March to May (slope difference, 0.10 [CI, 0.033 to 0.16]) despite greater corticosteroid use and more judicious intubation during later and higher-surging months. Nearly 1 in 4 COVID- 19 deaths (5868 [CI, 3584 to 8171]; 23.2%) was potentially attributable to hospitals strained by surging caseload. Limitation: Residual confounding. Conclusion: Despite improvements in COVID-19 survival between March and August 2020, surges in hospital COVID-19 caseload remained detrimental to survival and potentially eroded benefits gained from emerging treatments. Bolstering preventive measures and supporting surging hospitals will save many lives.