Utility of neutrophil to lymphocyte ratio to predict acute respiratory distress syndrome in COVID-19: short communication

Background:Acute respiratory distress syndrome (ARDS) is the most severe and devastating form of acute lung injury. Neutrophil to lymphocyte ratio (NLR) and C-reactive protein have been used to predict severity and prognosis of certain viral illnesses. Methods:A retrospective cohort study was conducted in hospitalized COVID-19 patients. Serial measurements of NLR and C-reactive protein were recorded and patients were followed for development of ARDS. Results:Out of 388 patients admitted with COVID-19, 43 patients developed ARDS compared with 345 patients who did not develop ARDS. The median NLR at presentation was significantly higher in patients who developed ARDS (8.89 vs. 4.25) compared with those who did not develop ARDS (P<0.001). Moreover, serial measurement of NLR at presentation, day 3, day 5 and day 7 was significantly associated with development of ARDS (P<0.001). In multivariable analysis, age of greater than or equal to 50 years (adsjusted odds ratio=3.28; 95% CI=1.40-7.69) and unit increase in NLR at presentation (adsjusted odds ratio=1.07; 95% CI=1.03-1.11) were independently associated with development of ARDS. Conclusion:Serial measurement of NLR can predict patients who are at a greater risk for developing ARDS in COVID-19.