June 10, 2019
2 min read

Flu-related hospitalization rates, risk for death increase with age among elderly

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Christopher A. Czaja, MD, MPH
Christopher A. Czaja

Among adults aged 65 years or older, increasing age was associated with higher rates of influenza-related hospitalizations and higher risk for death, according to findings from the U.S. Influenza Hospitalization Surveillance Network, or FluSurv-NET.

In the United States, approximately 46 million adults are aged 65 years or older and researchers said that this population is a “large and heterogeneous group.” Despite this, older adults are often categorized as a single age group for disease surveillance purposes, according to Christopher A. Czaja, MD, MPH, an antibiotic stewardship medical epidemiologist with the Colorado Department of Public Health and Environment, and colleagues wrote.

Therefore, using population-based surveillance data collected through FluSurv-NET, Czaja and colleagues evaluated age-related differences in influenza-associated hospitalization rates, clinical presentation and outcomes among 19,760 older adults with laboratory-confirmed influenza. They analyzed data from the 2011-2012 influenza season through the 2014-2015 season and stratified patients by age groups in 10-year intervals: 65 to 74 years, 75 to 84 years and 85 years or older.

“We found that rates of laboratory-confirmed influenza hospitalization and odds of severe outcomes, including pneumonia or in-hospital death or transfer to hospice, were higher in adults aged 75 to 84 years and adults aged 85 years and older compared to those aged 65 to 74 years,” Czaja told Infectious Disease News.

Infographic about flu-related hospitalizations 

Over four influenza seasons, the rates of hospitalizations among adults aged 65 to 74 years ranged from 101 to 417 per 100,000 persons, whereas rates ranged from 209 to 1,264 and 562 to 2,651 among adults aged 74 to 85 years and those aged 85 years or older, respectively.

Moreover, compared with adults aged 65 to 74 years, adults aged 75 to 84 years had hospitalization rates 1.4 to 3 times higher, and adults aged 85 years or older had rates 2.2 to 6.4 times higher.

Furthermore, patients aged 85 years or older had higher odds of pneumonia (adjusted OR = 1.2; 95% CI, 1-1.3) and in-hospital death or transfer to hospice (aOR = 2.1; 95% CI, 1.7-2.6), compared with adults aged 65 to 74 years.

“Clinicians should recognize that older adults of increasing age may present with a variety of typical and atypical risk factors, symptoms, and signs, and diagnose and treat influenza promptly and appropriately,” Czaja said. “Public health epidemiologists should analyze and report influenza surveillance data using additional age strata for older adults so that we may identify opportunities to improve preventive care. CDC now reports influenza-associated hospitalizations among older adults using additional age strata in FluView.” – by Marley Ghizzone

Disclosures: Czaja reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.