As of June 2023, more than 1.1 million Americans have died of COVID-19. Adults older than 65 —who make up just 16% of the population—account for more than 75% of U.S. COVID-19 deaths and were hospitalized at three times the rate of younger people, highlighting the heightened vulnerability of this population.

In a new study, Harvard Medical School researchers at Beth Israel Deaconess Medical Center used national Medicare data to characterize the long-term risk of death and hospital readmission after being hospitalized with COVID-19 among beneficiaries 65 years and older. The study, which appears in the BMJ, demonstrates that among individuals who were admitted to the hospital with COVID-19 and were discharged alive, the risk of post-discharge death was nearly twice that observed in those who were discharged alive from an influenza-related hospital admission.

“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.”

“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,” said co-senior author Dhruv Kazi, HMS associate professor of medicine, director of the cardiac critical care unit, and associate director of the Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology at Beth Israel Deaconess.

“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 research compared outcomes for more than one million Medicare beneficiaries admitted to the hospital with COVID-19 between March 2020 and August 2022 with nearly 58,000 Medicare beneficiaries admitted to the hospital for influenza between March 2018 and August 2019.

The physician-researchers observed that the patients hospitalized for COVID-19 had higher in-hospital mortality compared with the influenza patients (17 versus 3 percent), and that the increased risk of death after COVID-19 hospitalization persisted at 30, 90, and 180 days after discharge. The greatest difference in risk between the two groups was concentrated in the first 30 days after discharge.

Within the COVID-19 group, significant differences in race and socioeconomic status were found in post-discharge death at 180 days. Individuals enrolled in both Medicaid and Medicare had higher risk of death. Black patients had a higher risk of death compared with white patients, largely driven by an increased risk of rehospitalization. In contrast, the risk of death was slightly lower in Black patients compared with white patients at 180 days post-discharge.

“Individuals with low income and those from racial or 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,” said co-senior author Robert Yeh, HMS professor of medicine and director of the Smith Center at Beth Israel Deaconess. “We found that many of these inequalities persist among a cohort of patients who were discharged alive after COVID-19-related hospital admissions.”

“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.”

The COVID-19 patients also experienced a higher risk of hospital readmission at 30 and 90 days compared with the flu patients; however, by 180 days, the rate of readmissions were similar between the two groups. The most common reasons for readmission were circulatory conditions, respiratory conditions, sepsis, heart failure, and pneumonia. Within the COVID-19 group, Black individuals and dual-eligible beneficiaries were more likely to be readmitted than white patients.

Encouragingly, the scientists demonstrated a decline in post-discharge death over the course of the study period. The scientists note that several epidemiological factors may explain this 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, potentially fatal cases of COVID-19; and 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,” said lead author Andrew Oseran, an HMS research fellow in medicine 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.”

Authorship, funding, disclosures

Additional authors included Yang Song, Jiaman Xu, Issa J. Dahabreh, Rishi K. Wadhera, Tianyu Sun, James A. de Lemos, and Sandeep R. Das.

This work was supported by the National Heart, Lung, and Blood Institute (R01HL157530) and Patient-Centered Outcomes Research Institute (ME-1502- 27704). Sun’s involvement in this project occurred while he was employed at Smith Center before his current employment at Moderna. Dahabreh is the principal investigator of research agreement between Harvard and Sanofi on statistical methods for vaccine trials with applications to influenza, and he has received consulting fees from Moderna. The other authors report no financial relationships with any organizations that might have an interest in the submitted work in the previous three years and no other relationships or activities that could appear to have influenced the submitted work.

Originally published in Harvard Medical School News.