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. 2023 Nov 29;10(12):ofad599.
doi: 10.1093/ofid/ofad599. eCollection 2023 Dec.

Association of Chronic Medical Conditions With Severe Outcomes Among Nonpregnant Adults 18-49 Years Old Hospitalized With Influenza, FluSurv-NET, 2011-2019

Efemona A Famati  1   2 , Dawud Ujamaa  1   3 , Alissa O'Halloran  1 , Pam Daily Kirley  4 , Shua J Chai  4   5 , Isaac Armistead  6 , Nisha B Alden  6 , Kimberly Yousey-Hindes  7 , Kyle P Openo  8   9   10 , Patricia A Ryan  11 , Maya L Monroe  11 , Anna Falkowski  12 , Sue Kim  12 , Ruth Lynfield  13 , Melissa McMahon  13 , Kathy M Angeles  14 , Sarah A Khanlian  14 , Nancy L Spina  15 , Nancy M Bennett  16 , Maria A Gaitán  16 , Eli Shiltz  17 , Krista Lung  17 , Ann Thomas  18 , H Keipp Talbot  19 , William Schaffner  19 , Andrea George  20 , Holly Staten  20 , Catherine H Bozio  1 , Shikha Garg  1
Affiliations

Association of Chronic Medical Conditions With Severe Outcomes Among Nonpregnant Adults 18-49 Years Old Hospitalized With Influenza, FluSurv-NET, 2011-2019

Efemona A Famati et al. Open Forum Infect Dis. .

Abstract

Background: Older age and chronic conditions are associated with severe influenza outcomes; however, data are only comprehensively available for adults ≥65 years old. Using data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), we identified characteristics associated with severe outcomes in adults 18-49 years old hospitalized with influenza.

Methods: We included FluSurv-NET data from nonpregnant adults 18-49 years old hospitalized with laboratory-confirmed influenza during the 2011-2012 through 2018-2019 seasons. We used bivariate and multivariable logistic regression to determine associations between select characteristics and severe outcomes including intensive care unit (ICU) admission, invasive mechanical ventilation (IMV), and in-hospital death.

Results: A total of 16 140 patients aged 18-49 years and hospitalized with influenza were included in the analysis; the median age was 39 years, and 26% received current-season influenza vaccine before hospitalization. Obesity, asthma, and diabetes mellitus were the most common chronic conditions. Conditions associated with a significantly increased risk of severe outcomes included age group 30-39 or 40-49 years (IMV, age group 30-39 years: adjusted odds ratio [aOR], 1.25; IMV, age group 40-49 years: aOR, 1.36; death, age group 30-39 years: aOR, 1.28; death, age group 40-49 years: aOR, 1.69), being unvaccinated (ICU: aOR, 1.18; IMV: aOR, 1.25; death: aOR, 1.48), and having chronic conditions including extreme obesity and chronic lung, cardiovascular, metabolic, neurologic, or liver diseases (ICU: range aOR, 1.22-1.56; IMV: range aOR, 1.17-1.54; death: range aOR, 1.43-2.36).

Conclusions: To reduce the morbidity and mortality associated with influenza among adults aged 18-49 years, health care providers should strongly encourage receipt of annual influenza vaccine and lifestyle/behavioral modifications, particularly among those with chronic medical conditions.

Keywords: adults; chronic conditions; hospitalizations; influenza; severe.

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Conflict of interest statement

Potential conflicts of interest. D.U. reports that he is a contract employee of GDIT. K.Y.H. reports grants from the CDC for the Connecticut Emerging Infections Program. M.M. reports grants from the CDC for the Emerging Infections Program. P.R. reports funding support from the Emerging Infections Program Cooperative agreement. A.F. reports grants from the Michigan Department of Health and Human Services from the CSTE Federal Grand. S.K. reports grants from the Michigan Department of Health and Human Services from the CSTE Federal Grand. R.L. reports grants from the CDC Emerging Infections Cooperative Agreement to the MN Department of Health. S.K. reports salary and data collection for the manuscript supported by a grant received from the CDC Emerging Infections Program. K.A. reports salary and data collection for the manuscript supported by a grant received from the CDC Emerging Infections Program. N.B. reports an agreement to consult for the GSK. E.S. reports grant funding for the population-based Influenza Hospitalization Surveillance Project (IHSP) and COVID-Net activities, including support for personnel and equipment for data collection activities from the Council for State and Territorial Epidemiologists (CSTE). W.S. reports a grant from the CDC Emerging Infections Program. H.K.T. reports a grant from the CDC. A.G. reports a grant from the CSTE. All other authors report no potential conflicts.

Figures

Figure 1.
Figure 1.
FluSurv-NET study population, 2011–2012 to 2018–2019.
Figure 2.
Figure 2.
Distribution of underlying condition categories by age group, sex, and race/ethnicity, FluSurv-NET, 2011–2012 to 2018–2019.
Figure 3.
Figure 3.
Factors associated with severe outcomes among adults aged 18–49 years hospitalized with influenza, FluSurv-NET, 2011–2012 to 2018–2019. Each model (pneumonia, ICU admission, invasive mechanical ventilation, and in-hospital death) was adjusted for surveillance site, influenza season, age, sex, race/ethnicity, influenza vaccination status, tobacco use, any vs no underlying condition, and the following underlying condition categories: asthma, blood disorders/hemoglobinopathy, chronic lung disease, cardiovascular disease, metabolic disease, neurologic disease, immunocompromising condition, liver disease, extreme obesity. Abbreviation: ICU, intensive care unit.
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