Underlying Medical Conditions and Severe Illness Among 540,667 Adults Hospitalized With COVID-19

March 2020-March 2021

Lyudmyla Kompaniyets, PhD; Audrey F. Pennington, PhD; Alyson B. Goodman, MD; Hannah G. Rosenblum, MD; Brook Belay, MD; Jean Y. Ko, PhD; Jennifer R. Chevinsky, MD; Lyna Z. Schieber, DPhil, MD; April D. Summers, MPH; Amy M. Lavery, PhD; Leigh Ellyn Preston, DrPH; Melissa L. Danielson, MSPH; Zhaohui Cui, PhD; Gonza Namulanda, DrPH; Hussain Yusuf, MD; William R. Mac Kenzie, MD; Karen K. Wong, MD; James Baggs, PhD; Tegan K. Boehmer, PhD; Adi V. Gundlapalli, MD, PhD


Prev Chronic Dis. 2021;18(7):e66 

In This Article

Abstract and Introduction


Introduction: Severe COVID-19 illness in adults has been linked to underlying medical conditions. This study identified frequent underlying conditions and their attributable risk of severe COVID-19 illness.

Methods: We used data from more than 800 US hospitals in the Premier Healthcare Database Special COVID-19 Release (PHD-SR) to describe hospitalized patients aged 18 years or older with COVID-19 from March 2020 through March 2021. We used multivariable generalized linear models to estimate adjusted risk of intensive care unit admission, invasive mechanical ventilation, and death associated with frequent conditions and total number of conditions.

Results: Among 4,899,447 hospitalized adults in PHD-SR, 540,667 (11.0%) were patients with COVID-19, of whom 94.9% had at least 1 underlying medical condition. Essential hypertension (50.4%), disorders of lipid metabolism (49.4%), and obesity (33.0%) were the most common. The strongest risk factors for death were obesity (adjusted risk ratio [aRR] = 1.30; 95% CI, 1.27–1.33), anxiety and fear-related disorders (aRR = 1.28; 95% CI, 1.25–1.31), and diabetes with complication (aRR = 1.26; 95% CI, 1.24–1.28), as well as the total number of conditions, with aRRs of death ranging from 1.53 (95% CI, 1.41–1.67) for patients with 1 condition to 3.82 (95% CI, 3.45–4.23) for patients with more than 10 conditions (compared with patients with no conditions).

Conclusion: Certain underlying conditions and the number of conditions were associated with severe COVID-19 illness. Hypertension and disorders of lipid metabolism were the most frequent, whereas obesity, diabetes with complication, and anxiety disorders were the strongest risk factors for severe COVID-19 illness. Careful evaluation and management of underlying conditions among patients with COVID-19 can help stratify risk for severe illness.


As the COVID-19 pandemic continues, a need remains to understand indicators for severe illness, defined as admission to an intensive care unit (ICU) or stepdown unit, invasive mechanical ventilation (IMV), or death.[1] Several underlying medical conditions among adults, including diabetes, obesity, chronic kidney disease (CKD), hypertension, and immunosuppression, have been reported to be associated with increased risk for severe illness from COVID-19.[2–4] However, many existing studies are limited in geographic representation, restricted to cases early in the outbreak, or focused on a limited number of preselected conditions and/or severe outcomes.[3–5] Finally, few studies have shown the effect of the number of underlying medical conditions on the risk for severe COVID-19 illness.[6]

Both the baseline prevalence of a condition and the magnitude of its association with COVID-19 illness help determine the impact of a condition at a population level. This study, based on a large electronic administrative discharge data set, sought to describe the most frequent underlying medical conditions among hospitalized patients with COVID-19 and their associations with severe illness. This information can better inform clinical practice and public health priorities, such as identifying populations for focused prevention efforts and potential vaccine prioritization.