Boston—Despite the commonly heard claim at the height of the COVID-19 pandemic, SARS-CoV-2 appears to have been much riskier than influenza, at least in older adults who were hospitalized.

A new report in BMJ noted that as of June 2023, more than 1.1 million Americans have died of COVID-19, and more than 75% of them were aged older than 65 years. That group, which makes up just 16% of the population, also was hospitalized at three times the rate of younger cohorts.

A study from Beth Israel Deaconess Medical Center (BIDMC) in Boston used national Medicare data to document the long-term risk of death and hospital readmission for beneficiaries aged 65 years and older after being hospitalized with COVID-19.

The results suggested that for patients admitted to the hospital with COVID-19 and discharged alive, the risk of postdischarge death was nearly twice that observed in a group of similar patients hospitalized for influenza.

“Since the early days of the pandemic, it has been evident that older adults bear a disproportionate burden of COVID-19 and our study provides several important insights into the longer-term clinical consequences of the disease in this vulnerable population,” stated cosenior author Dhruv S. Kazi, MD, MSc, MS, of BIDMC. “We know that patients who require hospital admission for COVID-19 have more comorbidities, more severe initial disease and worse short-term outcomes compared with patients who are asymptomatic or mildly symptomatic, and they may be more vulnerable to late complications of infection. Our goal was to better understand long-term outcomes after patients are discharged from the hospital so as to help tailor support strategies and guide resource allocation for future surges of COVID-19 or during future pandemics.”

The retrospective cohort study involved 883,394 Medicare fee-for-service beneficiaries aged 65 years and older who were discharged alive after an index hospital admission with COVID-19 between March 1, 2020, and August 31, 2022. Those patients were compared with 56,409 historical controls discharged alive after hospital admission with influenza between March 1, 2018, and August 31, 2019.

The researchers focused on all-cause death within 180 days of discharge, with first all-cause readmission and a composite of death or readmission within 180 days considered secondary outcomes.

The researchers noted that the COVID-19 cohort was younger than the influenza cohort (77.9 vs. 78.9 years, standardized mean difference [SMD] –0.12) and had a lower proportion of women (51.7% vs. 57.3%, SMD –0.11). Both groups had a similar proportion of black beneficiaries (10.3% vs. 8.1%, SMD 0.07) and beneficiaries with dual Medicaid-Medicare eligibility status (20.1% vs. 19.2%; SMD 0.02).

In addition, the participants with COVID-19 had a lower comorbidity burden, including atrial fibrillation (24.3% vs. 29.5%, SMD –0.12), heart failure (43.4% vs. 49.9%, SMD –0.13), and chronic obstructive pulmonary disease (39.2% vs. 52.9%, SMD –0.27).

After weighting, the researchers determined that the COVID-19 cohort had a higher risk (i.e., cumulative incidence) of all-cause death at 30 days (10.9% vs. 3.9%; standardized risk difference [SRD] 7.0%, 95% CI, 6.8%-7.2%), 90 days (15.5% vs. 7.1%; SRD 8.4%, 8.2%-8.7%), and 180 days (19.1% vs. 10.5%; SRD 8.6%, 8.3%-8.9%) compared with the influenza cohort.

“The COVID-19 cohort also experienced a higher risk of hospital readmission at 30 days (16.0% vs. 11.2%; 4.9%, 4.6% to 5.1%) and 90 days (24.1% vs. 21.3%; 2.8%, 2.5% to 3.2%) but a similar risk at 180 days (30.6% vs. 30.6%; –0.1%, –0.5% to 0.3%),” the authors wrote. “Over the study period, the 30-day risk of death for patients discharged after a COVID-19 admission decreased from 17.9% to 7.2%.”

The study concluded that while Medicare beneficiaries who were discharged alive after a COVID-19 hospital admission had a higher postdischarge risk of death compared with historical influenza controls, the difference was concentrated in the early postdischarge period. “The risk of death for patients discharged after a COVID-19 related hospital admission substantially declined over the course of the pandemic,” the researchers added.

Within the COVID-19 cohort, significant differences were identified in the 180-day risk of postdischarge death when race and socioeconomic status were considered. For example, patients enrolled in both Medicaid and Medicare had a higher risk of death, and black patients had a higher risk of death or rehospitalization compared with white patients, largely driven by an increased risk of rehospitalization. Overall, however, the risk of death was slightly lower in black patients compared with white patients.

“Individuals with low income and those from racial/ethnic minority populations have been shown to be at increased risk for adverse events associated with acute COVID-19, including higher rates of infection, hospital admissions and in-hospital death,” stated cosenior author Robert W. Yeh, MD, MSc, of BIDMC. “We found that many of these inequalities persist among a cohort of patients who were discharged alive after COVID-19-related hospital admissions.”

In terms of the decline in postdischarge deaths, the authors pointed to several epidemiological factors to help explain the trend:

• Clinicians have made major advances in treating patients hospitalized with severe cases of COVID-19.
• Vaccination campaigns targeting high-risk patient populations, including older adults, may have prevented many infections from becoming severe and potentially fatal cases of COVID-19.
• The virus itself may be undergoing changes in virulence.

“While we did find that rates of death following a hospitalization for COVID-19 steadily declined over the course of the pandemic, the substantial in-hospital and early post-discharge risk of death associated with COVID-19 in this sample of Medicare beneficiaries highlights the need for preventative interventions, particularly in patients at increased long-term risk for adverse outcomes,” explained lead author Andrew S. Oseran, MD, MBA, a research fellow at Massachusetts General Hospital. “Our findings suggest the continued need to evaluate clinical and societal interventions that address the glaring inequities in post-discharge outcomes among older adults hospitalized with COVID-19.”

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