IntroductionCOVID-19 affects the hematologic system. This article evaluated the impact of hematologic involvement of different blood cell line parameters of white blood cells including absolute neutrophil count (ANC), hemoglobin, and platelets in COVID-19 patients and their association with hospital mortality and length of stay (LOS).MethodsThis was a retrospective study of 475 patients with confirmed positive COVID-19 infection and hematologic abnormalities in the metropolitan New York City area.ResultsElevated absolute neutrophil count (OR: 1.20; 95% CI: 1.02–1.42; p < 0.05) increased days of hematologic involvement (OR: 4.44; 95% CI: 1.42–13.90; p < 0.05), and persistence of hematologic involvement at discharge (OR: 2.87; 95% CI: 1.20–6.90; p < 0.05) was associated with higher mortality. Higher hemoglobin at admission (OR: 0.77; 95% CI:0.60–0.98; p < 0.001) and platelets peak (OR: 0.995; 95% CI: 0.992–0.997; p < 0.001) were associated with decreased mortality. Patients with higher white blood cell peak (B = 0.46; SE = 0.07; p < 0.001) and higher hemoglobin at admission (B = 0.05; SE = 0.01; p < 0.001) were associated with higher LOS. Those with higher hemoglobin nadir (B = −0.06; SE = 0.01; p < 0.001), higher platelets nadir (B = −0.001; SE = < 0.001; p < 0.001), and hematologic involvement at discharge or death (B = −0.06; SE = 0.03; p < 0.05) were associated with lower LOS.ConclusionsThese findings can be used by clinicians to better risk-stratify patients with hematologic involvement in COVID-19 and tailor therapies potentially to improve patient outcomes.