Study establishes a link between surges in COVID-19 cases and risk of mortality at hospitals

Statistical analysis shows nearly a quarter of COVID-19 deaths during the first six months of the pandemic could be ascribed to high caseloads at hospitals.

A new study quantifies the relationship between surges in COVID-19 cases at hospitals and mortality rates during the early months of the pandemic.

“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,” researchers with the National Institutes of Health wrote in a study published July 6 in the Annals of Internal Medicine. “Bolstering preventive measures and supporting surging hospitals will save many lives.”

For each month between March and August 2020, the researchers stratified 558 hospitals in a national database according to COVID-19 caseload relative to pre-COVID-19 bed capacity. Caseloads were weighted based on variables related to severity, such as number of cases for which invasive ventilation was required.

The researchers then examined whether there was an association between a hospital’s caseload and COVID-19 patients’ risk-adjusted odds ratio of in-hospital mortality or discharge to hospice.

COVID-19 mortality decreased across hospitals during the study period. However, compared with hospitals in the lower half of the “surge index,” those in the upper half had a risk-adjusted mortality odds ratio of at least 1.11. The odds ratio increased to 1.42 for hospitals in the 90^th percentile, 1.59 for hospitals in the 95^th percentile and 2 for hospitals in the 99^th percentile.

The statistical relationship between case surge and mortality was stronger in June, July and August 2020 compared with March, April and May, “despite greater corticosteroid use and more judicious intubation during later and higher-surging months,” the researchers wrote.

Overall, 23.2% of COVID-19 deaths were “potentially attributable to hospitals strained by surging caseload.”

Applying the findings in future scenarios

Although the study did not establish causation, the researchers said the findings are strong enough to “suggest potential value in prioritizing staffing, inventory and logistical support early, especially to select hospitals approaching concerning surge index thresholds. Doing so might prepare these hospitals to better manage patients with COVID-19 in the event of even greater and more prolonged surges.”

New approaches to triaging and diversion may also be warranted in preparation for future surges of COVID-19 or for another disease outbreak.

“Our data raise the question of whether there may be a role for earlier diversion of patients with COVID-19 from emergency departments of hospitals experiencing surges,” the researchers wrote. “Preemptive engagement of relief healthcare (‘shock absorber’) facilities is already occurring. Medical operations coordination cells are enabling these triage efforts to cross state lines, especially when neighboring hospitals are also experiencing surges.

“However, the risks and benefits of transporting patients with COVID-19 must be carefully studied and calibrated to individual hospitals’ capacity, infrastructure and resources.”

Among the limitations of the study, the researchers wrote, was an inability to track the impact of changes in “the treatment paradigm” that might have boosted hospitals’ readiness for the COVID-19 surge that took hold in late 2020 and early 2021.

Specifically, “hospitals have had growing situational awareness, lead time for planning, and federal and state support over time.”