Mortality Risk Factors Identified for Hospitalized COVID-19 Patients

A new study reveals that age is the most important predictor of all-cause mortality in COVID-19 patients, with vital signs and laboratory results also playing a role.

Researchers at Genentech (San Francisco, CA, USA) conducted a retrospective cohort study in order to develop a prognostic algorithm that could identify and quantify mortality risk factors among patients admitted to the hospital with COVID-19. In all, 17,086 patients hospitalized between February 20 and June 5, 2020 were randomly assigned to either training (80%) or test (20%) sets. The full model included information on demographics, comorbidities, laboratory results, and vital signs. The main outcome measure was all-cause mortality during hospital stay.

The results revealed that age predicted the odds of death very significantly. Laboratory markers such as higher aspartate aminotransferase (AST), troponin, C-Reactive Protein (CRP), and white blood cell (WBC) counts, as well as creatinine and Lactate Dehydrogenase (LDH), were all linked to a higher risk of death, along with thrombocytopenia. In addition, vital signs at admission, such as low oxygen saturation (SpO₂), high respiratory and heart rate, high temperature, and high body mass index (BMI), were also found to be associated with a higher risk of death.

Age exponentially increases the risk of death, with the slope becoming ever steeper as age increased. At 75 years of age, the risk was six-fold higher than at 49 years. For example, the risk of death for a 70-year old and an 80-year-old COVID-19 patient who required hospitalization was 24% and 34%, respectively, but was only 2% for an 18-year-old patient. Other significant risk factors identified were the presence of advanced cancer; liver disease other than in mild degrees; hemiplegia or paraplegia; and dementia. The study was published on September 26, 2020, in medRxiv.

“The strong effect of age might be because it not only links to the comorbidities that are listed in the model, but also others that may cause a worse outcome,” concluded lead author senior data scientist Devin Incerti, PhD, and colleagues. “Again, advancing age is known to be a predictor of decreased immune function, leading to increased viral persistence, or to an uncontrolled immune response that may cause severe clinical features in COVID-19.”

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