Red blood cell distribution width (RDW) measures the variation of red blood cell volumes, study authors wrote. An elevated RDW raises the risk of mortality from an onslaught of health issues, including heart disease, pulmonary disease, influenza and cancer, said the study published in JAMA Network Open. Though “a definitive mechanism for RDW elevation has not yet been established,” authors concluded that this component in the blood could offer patient risk-stratification for COVID-19.
They did, however, mention one possibility: "An elevated RDW in some circumstances may reflect a clinical state in which RBC production and turnover have slowed in the setting of increased production and turnover of leukocytes or platelets such as would occur in inflammation."
Previous studies have examined other biomarkers in the blood to assess COVID-19 severity. One study from George Washington University, for example, pointed to five biomarkers associated with poor outcomes from coronavirus: CRP, D-dimer, IL-6, LDH, and ferritin.
In the study at hand, the authors wrote that “elevated RDW at admission and increasing RDW during hospitalization were associated with statistically significant increases in mortality risk."
The mortality risk was 11% among patients with a normal RDW and 31% in patients with an elevated RDW. (An elevated RDW was defined as over 14.5%.)
The researchers from Massachusetts General Hospital studied 1,641 adults with COVID-19 admitted across four hospitals in Boston between March 4 and April 28. The association between increased mortality risk and elevated RDW was upheld even after accounting for factors including age, race, ethnicity, and common comorbidities.
Researchers said the baseline figures for the patients with elevated RDW are unknown, and further studies are needed during the earlier stages of the disease to see “how quickly RDW may be evolving before hospitalization."
Nevertheless, the study highlights the importance of "early, aggressive intervention" for at-risk patients, and the best management of hospital resources.
Fox News has requested comment from Cleveland Clinic and Johns Hopkins University, among others, over a potential shift toward RDW in predicting COVID-19 severity.