In-hospital delirium linked to long-term cognitive impairment in COVID-19 patients over 60

In a recent study published in the JAMA Network Open, a group of researchers evaluated the association of in-hospital delirium (sudden, severe confusion and brain function changes) with functional disability and cognitive impairment (decline in memory and thinking skills) over the six months following discharge among older adults hospitalized with coronavirus disease 2019 (COVID-19).

Study: In-Hospital Delirium and Disability and Cognitive Impairment After COVID-19 Hospitalization. Image Credit: BlurryMe/Shutterstock.comStudy: In-Hospital Delirium and Disability and Cognitive Impairment After COVID-19 Hospitalization. Image Credit: BlurryMe/


Older adults are more likely to experience severe illness from COVID-19, often requiring hospitalization and intensive care unit (ICU) admission.

Delirium is common among these patients and is reported as the sixth most frequent symptom in older adults presenting to the emergency department. Delirium rates in hospitalized COVID-19 patients range from 11% to 65%.

It is a significant risk factor for complications such as prolonged hospital stays, unplanned ICU admissions, discharge to nursing facilities, and increased mortality. The pandemic exacerbated delirium risk factors, including prolonged hospital stays, sedatives, social isolation, immobility, and communication barriers.

Further research is needed to understand better the long-term impacts of in-hospital delirium on functional and cognitive outcomes in older adults post-COVID-19 hospitalization.

About the study 

Participants were drawn from the COVID‐19 in Older Adults: A Longitudinal Assessment (VALIANT) cohort, a prospective study assessing outcomes among older COVID-19 survivors hospitalized at five Yale-New Haven Health System hospitals.

Eligibility required participants to be at least 60 years old, speak English or Spanish, and have a confirmed Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection.

Exclusions included advanced dementia, long-term nursing facility residency, or hospice transition. Verbal informed consent was obtained, and proxies were used if decisional impairment was confirmed.

Enrolled between June 18, 2020, and June 30, 2021, participants had follow-ups through January 11, 2022. Baseline and follow-up data on physical function, cognition, and symptoms were collected remotely at 1, 3, and 6 months post-discharge. The follow-up rate was 92.7%.

The study was approved by the Yale University institutional review board and adhered to Strengthening the Reporting of Observational Studies in Epidemiology (STROBE)  guidelines.

Demographic data, including race and ethnicity, were extracted from electronic medical records due to COVID-19’s disproportionate impact on minoritized groups. Prehospitalization functional status was assessed at baseline, and preexisting cognitive impairment was noted. Details of the index hospitalization were also recorded.

Disability in 15 activities and cognition via the Montreal Cognitive Assessment (MoCA) 5-minute protocol were assessed at follow-ups. Delirium during hospitalization was identified using Chart-Based Delirium Identification Instruments (CHART-DEL) instruments.

Models adjusted for age, follow-up month, and baseline outcomes evaluated the association between in-hospital delirium and functional and cognitive impairments, with statistical significance defined as P < .05.

Study results 

The mean age of the functional disability sample, consisting of 311 patients, was 71.3 years, with 52.4% female. Over one-third of the participants were from minoritized racial and ethnic groups, including Asian, Black Hispanic, Black non-Hispanic, Hispanic, and White Hispanic individuals. Among these participants, 31.8% had Medicaid insurance.

In the functional disability sample, 15.8% experienced in-hospital delirium, while in the cognition sample of 271 participants, 11.4% experienced in-hospital delirium. Participants with in-hospital delirium were older than those without delirium and had greater preexisting disabilities in functional activities and prehospitalization cognitive impairment.

A higher proportion of delirium patients were admitted to the stepdown unit or ICU and required mechanical ventilation. In the functional disability cohort, 9.3% were admitted to the ICU. The 6-month follow-up rate in the analytic sample was 96.4%.

Before hospitalization, the mean disability count among participants with in-hospital delirium was 4.0, which increased to 6.6 at one month post-discharge and 5.3 at six months. In participants without in-hospital delirium, the mean disability count was 1.8 before hospitalization, rising to 2.7 at one month and 2.1 at six months.

Multivariable modeling indicated that in-hospital delirium was associated with an increased disability count over six months post-COVID-19 hospitalization (rate ratio, 1.32).

Cognitive impairment before hospitalization was present in 9.7% of participants with in-hospital delirium and 2.9% of those without. At one month post-discharge, 63.6% of delirium patients experienced cognitive impairment compared to 22.6% of non-delirium patients.

At three months, the proportion of participants with cognitive impairment was approximately 14% in both groups, though there was more missing data among participants with cognitive impairment.

At six months, 34.8% of participants with delirium had cognitive impairment, compared to 20.7% without delirium. Multivariable analysis showed that in-hospital delirium was associated with cognitive impairment over six months post-COVID-19 hospitalization (odds ratio, 2.48).


To summarize, it was found that in-hospital delirium was associated with increased rates of functional disability and cognitive impairment over the six months post-discharge. Delirium, a severe complication of COVID-19, has been linked to worse outcomes such as increased mortality, ICU admission, and prolonged hospital stays.

In this study, 15.8% of participants experienced delirium, consistent with previous reports of 11% to 65%. The study underscores the importance of implementing evidence-based interventions to prevent delirium and mitigate its long-term effects.

Journal reference:
Vijay Kumar Malesu

Written by

Vijay Kumar Malesu

Vijay holds a Ph.D. in Biotechnology and possesses a deep passion for microbiology. His academic journey has allowed him to delve deeper into understanding the intricate world of microorganisms. Through his research and studies, he has gained expertise in various aspects of microbiology, which includes microbial genetics, microbial physiology, and microbial ecology. Vijay has six years of scientific research experience at renowned research institutes such as the Indian Council for Agricultural Research and KIIT University. He has worked on diverse projects in microbiology, biopolymers, and drug delivery. His contributions to these areas have provided him with a comprehensive understanding of the subject matter and the ability to tackle complex research challenges.    


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