Last Reviewed: November 9, 2021
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The following is a curated review of key information and literature about this topic. It is not comprehensive of all data related to this subject.
Overview
Older adults are more susceptible to COVID-19 than other age groups and experience high morbidity and mortality. Despite comprising 17% of the U.S. population, individuals >65 years of age accounted for 31% of first-wave COVID-19 cases (February-March 2020), 45% of hospitalizations, 53% of ICU admissions and 80% of deaths (CDC, March 2020). People aged >85 years were 13-fold more likely to require hospitalization and 630-fold more likely to die of COVID-19 compared to adults aged 18-29 (CDC, April 2020).
In addition to common COVID-19 symptoms such as fever, cough and dyspnea, older adults may have atypical and insidious presentations. Delirium is particularly common, whereas fever response may be blunted (Kennedy, November 2020). Other symptoms such as cough, arrhythmia and impaired mobility may be confused with exacerbation of chronic conditions such as heart failure or COPD (Nanda, May 2020). Chest computed tomography may also vary, with a higher percentage of consolidative opacities and lower percentage of cases of more “classic” ground glass opacification reported in older adults (Song, February 2020). As such, clinicians should have a low threshold for testing for the disease in older patients seeking emergency medical care during periods of COVID-19 transmission in the community (Osuafor, February 2021).
COVID-19 complications are common in the elderly, including acute respiratory distress syndrome and prolonged ventilatory support, acute kidney injury, cardiac injury, liver dysfunction, shock and death (Nanda, May 2020). This may be related to age-related declines in respiratory function (Perrotta, 2020) as well as "immunosenescence,” i.e., disruption of the innate and adaptive arms of the immune system, including reduced ability to respond to new antigens, an accumulation of memory T-cells and a lingering level of low-grade inflammation with advancing age. Intensity and duration of post-acute symptoms of SARS-CoV-2 infection in this group are uncertain (Nikolich-Zugich, April 2020). Regardless, social distancing measures and isolation negatively impact the mental and physical health of older adults, resulting in an increased incidence of cardiovascular disease, stroke, depression, anxiety, dementia and premature death (Lithander, July 2020).
Despite the link between age and severe COVID-19 outcomes, health providers should note that older adults are a heterogenous group with varying vulnerability. Male sex and several specific comorbidities (e.g., obesity, hypertension, diabetes, COPD, coronary heart disease, malignant tumors and dementia) may independently increase risk of infection and predict poorer outcomes in older COVID-19 patients (Lithander, July 2020; Wang, February 2021). Measures of frailty — the medical syndrome characterized by diminished functional capacity —- may be a better predictor of COVID-19 outcomes than either age or comorbidity (Hewitt, June 2020).
In this review, we summarize select key epidemiologic literature discussing COVID-19 in the older adult population. Multiple studies on this topic have been published; therefore, we focus on the largest studies and the studies with the highest level of evidence and most generalizable results.
Key Literature
Delirium
Delirium in Older Patients with COVID-19 Presenting to the Emergency Departments (Kennedy, November 2020).
Overall, in a moderately-sized cohort of older adults presenting to emergency departments with COVID-19, delirium was common and often present sans other “typical” COVID-19 symptoms. Delirium was associated with poor hospital outcomes and death.
Patient population:
- Multicenter cohort study across 7 U.S. emergency departments with 817 adults ≥65 years presenting consecutively with COVID-19 on or after March 13, 2020.
- Participants were 47% male, 27% Black and 7% Hispanic/Latino.
- Mean (SD) age was 77.7 (8.2) years.
Primary endpoint:
- Frequency of delirium in older adults presenting to the emergency department with COVID-19 and associated hospital outcomes.
Results:
- 226 participants (28%) had delirium at presentation;
- Of these, 37 (16%) had delirium as a primary symptom, while 84 (37%) had no other typical COVID-19 symptoms or signs (e.g., fever).
- Factors associated with delirium were:
- Age >75 (aRR, 1.51; 95% CI, 1.17-1.95);
- Nursing home or assisted living (aRR, 1.23; 95% CI, 0.98-1.55);
- Prior psychoactive medication (aRR, 1.42; 95% CI, 1.11-1.81);
- Vision impairment (aRR, 1.98; 95% CI, 1.54-2.54);
- Hearing impairment (aRR, 1.10; 95% CI 0.78-1.55);
- Stroke (aRR, 1.47; 95% CI, 1.15-1.88);
- Parkinson’s disease (aRR, 1.88; 95% CI, 1.30-2.58).
- Delirium was associated with ICU stay (aRR, 1.67; 95% CI, 1.30-2.15) and death (aRR, 1.24; 95% CI, 1.00-1.55).
Limitations:
- Retrospective review may have underestimated or misreported delirium prevalence.
- Not able to assess differences among study sites.
- Some missing demographic data.
- Large proportion of persons in assisted living facilities or nursing homes and/or with prior diagnosis of dementia, which may limit generalizability.
Delirium and Adverse Outcomes in Hospitalized Patients with COVID‐19 (Garcez, August 2020).
Overall, in a sample of patients ages >=50 years admitted with COVID-19, delirium was seen in one-third of patients and was independently associated with severe disease, ICU care and in‐hospital mortality.
Patient population:
- Longitudinal observational study in a Brazilian tertiary university hospital dedicated to the care of severe COVID-19 cases.
- 707 participants aged >=50 years, consecutively admitted to the hospital between March and May 2020.
- Mean participant age of 66 years (SD 11); 57% (402) male.
Primary endpoint:
- Occurrence of delirium in hospitalized patients with COVID‐19 and association with adverse outcomes.
Results:
- 234 (33%) experienced delirium overall, including 86 (12%) with delirium on admission
- In‐hospital mortality was 39% (N = 273); 55% in patients who experienced delirium versus 30% in those who did not (P <.001).
- Delirium was associated with in‐hospital death, with an adjusted odds ratio of 1.75 (95% CI, 1.15–2.66).
- Delirium also independently associated with length of hospital stay (adjusted incidence rate ratio, 1.36; 95% CI, 1.24–1.50), ICU admission (aOR, 3.32; 95% CI 2.11–5.23), and mechanical ventilation (aOR,1.99; 95% CI 1.30–3.05)
Limitations:
- Used chart-based metric (CHART-DEL) to identify delirium, which could lead to misclassification, particularly in persons with dementia.
- No information on delirium duration, severity and its temporal association with intensive care and other therapeutic measures.
- Single center, highly complex care facility which may limit generalizability.
Frailty
Age and frailty are independently associated with increased COVID-19 mortality and increased care needs in survivors: results of an international multicenter study (Geriatrics Medicine Research Collaborative, 2021).
Overall, age, frailty and comorbidity were independently associated with adverse outcomes in patients hospitalized with COVID-19 in this international, multicenter study. In particular, older and frailer patients were less likely to receive ICU care and were more likely to die, and survivors were more likely to require higher care levels upon discharge.
Patient population:
- Multicenter cohort study of 5,711 hospitalized COVID-19 patients >=18 years in 55 hospitals across 12 countries.
- Median participant age was 74 years; 55.2% were male.
Primary endpoint:
- Association of age, frailty and delirium with severe disease, mortality and transitions of care.
Results:
- 36% were rated 1-3 on the Clinical Frailty Scale (low) versus 17% >=7 (high).
- Independent associations with mortality were advanced age (>80 versus 18–49: HR, 3.57; 95% CI, 2.54–5.02) and frailty (Clinical Frailty Scale 8 versus 1–3: HR, 3.03; 95% CI, 2.29–4.00), but not delirium.
- Age, frailty, dementia, delirium, mental health diagnoses all associated with increased likelihood of higher care needs on discharge. Incidence of adverse outcomes increased from CFS scores 4 through 9.
- Age and frailty together (not individually) improved likelihood model fit (LR χ2 (7) = 91.3, P <0.001; Wald χ2 (10) = 207.9, P <0.001).
Limitations:
- Only including hospitalized cases, possibly selecting for frailer and sick population (who in turn may be less likely to pursue ICU care and thus suffer higher mortality).
- Missing BMI and ethnicity/race data.
The effect of frailty on survival in patients with COVID-19 (COPE): a multicenter, European, observational cohort study (Hewitt, August 2020).
Overall, increasing frailty was associated with both earlier death and longer time spent in the hospital in this large multicenter population of admitted older adults with COVID-19. Disease outcomes were better predicted by scores on the Clinical Frailty Scale than either age or comorbidity.
Patient population:
- Observational multicenter European cohort study of 1,564 adults hospitalized with COVID-19.
- The median age was 74 years (IQR 61–83); 903 (58%) participants were male.
Primary endpoint:
- Prevalence of frailty in hospitalized patients with COVID-19 and association with mortality and length of stay.
Results:
- 415 participants (27%) had diabetes, 804 (51%) had hypertension and 345 (22%) had coronary artery disease.
- 1,125 (72%) had increased C-reactive protein and 570 (36%) had impaired renal function.
- 772 (49%) were classified as frail (clinical frailty score 5-8) and 27 (2%) were terminally ill (CFS score = 9).
- Morality was 27% at data cutoff. Adjusted hazard ratio for time to death increased by CFS scale: 1.6 (CFS 3-4) vs. 1.8 (CFS 5-6) vs. 2.4 (CFS 7-9) higher HR vs. least frail (CFS 1-2) group. Adjusted odds ratios for day-7 mortality similarly increased by CFS scale: 1.22 (95% CI 0.63-2.38) for CFS 3-4, 1.62 (0.81-3.26) for CFS 5-6 and 3.12 (1.56-6.24) for CFS 7-9.
Limitations:
- Reflects first-wave data from Europe, predominately in the U.K.
- Utilized CFS scale which is not well validated in persons <65 years of age.
- Did not include BMI data.
- Did not include persons discharged or who died in the emergency department (i.e., potential extremes of illness severity), limiting generalizability to only admitted patients.
Dementia
COVID-19 and dementia: Analyses of risk, disparity and outcomes from electronic health records in the U.S. (Wang, February 2021).
Overall, after adjusting for multiple comorbidities, patients with dementia have 2-3-fold higher odds of admission for COVID-19, with high mortality.
Patient population:
- Retrospective case-control analysis of 62 million patient electronic health records in the United States up to Aug. 21, 2020.
- 1 million people represented had a diagnosis of dementia (1.7%): Alzheimer’s (0.6%); post-traumatic (0.1%); senile (0.3%); and vascular dementia (0.2%).
- 15,700 people represented were diagnosed with COVID-19, including 810 with dementia.
Primary endpoint:
- Risks and outcomes for patients with dementia infected with SARS-CoV-2.
Results:
- Odds ratio for COVID-19 diagnosis among persons with dementia vs. without dementia was 2.0 (95% CI, 1.94-2.06), after adjusting for age, sex, race, cardiovascular disease, pulmonary disease and other clinical factors, particularly among Black patients (aOR 2.9).
- Overall 6-month hospitalization risk , rising to 60% among those with COVID-19 plus dementia.
- Overall 6-month mortality was 5.6% versus 21% among patients with dementia (similar between Black and White patients) .
Limitations:
- Retrospective analysis as means to diagnose dementia. Limited information on social determinants of health. Association study that ultimately only focused on 810 persons with dementia and COVID-19, despite the large original sample.
Clinical Features
Clinical features and inpatient trajectories of older patients with COVID-19: a retrospective observational study (Osuafor, February 2021)
Overall, frailer older adult inpatients with COVID-19 infection had fewer typical symptoms of COVID-19 and higher morality versus less frail older adults.
Patient population:
- Retrospective observational study of 214 hospitalized U.K. COVID-19 inpatients aged >=65 years admitted via the emergency department March 1-May 15, 2020.
Primary endpoint:
- Clinical features and inpatient trajectory of older inpatients with confirmed COVID -19.
Results:
- 66% of patients were frail with median Clinical Frailty Scale score of 6.
- Frailer patients were less likely to fever (69% vs. 82%), cough (57% vs. 76%), myalgia (9% vs. 32%), fatigue (41% vs. 63%), diarrhea (9% vs. 32%) or loss of taste/smell (2% vs. 10%).
- Atypical symptoms more common , including confusion (21% vs. 45%).
- Mean length of stay was 11 days (range 6-18).
- 65% of patients were discharged and 35% died.
- In particular, male sex (aHR, 2.05; 95% CI, 1.3-3.3), older age (aHR, 1.04/year), more severe illness and higher frailty (aHR, CFS 7-8 vs. CFS 1-5 = 2.53; 95% CI, 1.24, 5.18) were independently associated with mortality; there was a dose-response association between higher CFS and mortality.
Limitations:
- This was a single-site, retrospective, observational study in U.K. with a relatively small sample.
- Not all patients appeared to have been formally assessed for frailty, requiring electronic health record supplementation.
- Utilization of ICU care may differ between countries for frail persons, affecting mortality rate.
Acute Care of Older Patients with COVID-19: Clinical Characteristics and Outcomes (Steinmeyer, September 2020).
Overall, among very old patients hospitalized with COVID-19, clinical presentations were frequently atypical, and although frailty was not associated with mortality, respiratory failure and lymphopenia were.
Patient population:
- Retrospective cohort study of 94 with confirmed or probable COVID-19 across 3 geriatrics wards in France from March to May 2020.
- 64 participants had confirmed COVID-19 cases and 30 had probable cases.
- Mean participant age was 86 years; 55% were female.
- 77% of patients were dependent on others for care; 45% were malnourished.
Primary endpoint:
- Clinical characteristics and outcomes of older patients hospitalized with COVID-19.
Results:
- Leading reasons for admission were fever (30%), dyspnea (28%) and geriatric syndromes such as falls, delirium (18%).
- There was no correlation between frailty and morality, though acute respiratory failure and lymphopenia were significantly associated.
Limitations:
- Small sample size in a very old and frail population, limiting generalizability to all older adults.