Association found between caseload surge and COVID-19 survival in 558 U.S. hospitals

July 9, 2021

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, according to an article posted by Annals of Internal Medicine and ACP Journals. 

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. 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. 

Of 144,116 inpatients with COVID-19 at 558 U.S. hospitals, 78,144 (54.2%) were admitted to hospitals in the top surge index decile. Overall, 25,344 (17.6%) died; crude COVID-19 mortality decreased over time across all surge index strata. 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 despite greater corticosteroid use and more judicious intubation during later and higher-surging months. Nearly one in four COVID-19 deaths (5868; 23.2%) was potentially attributable to hospitals strained by surging caseload. 

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. 

Many U.S. hospitals have contended with large surges in COVID-19 caseloads during the pandemic. Rapidly escalating demand relative to staff availability and burnout, space, supplies, and personal protective equipment might affect care and survival. Decreased intensive care unit (ICU) bed availability and increasing community case burden have been implicated as risk factors for poor COVID-19 outcomes. A hypothesis-generating study reported that patients with COVID-19 admitted during periods of higher-than-usual ICU demand had higher case-fatality rates. However, the study's nearly all-male cohort from 88 Department of Veterans Affairs hospitals limits generalizability, and the absence of surging ICU caseloads in later study months suggests that temporal improvements could explain their findings.

Temporal improvements in hospital survival rates for COVID-19 have been widely reported. However, wide variability in hospital survival reported even among contemporaneously admitted patients within and between regions suggests that differences in capacity and resources across hospitals and over time might have contributed to outcomes. 

ACP Journals has the article

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