Immature platelets as a biomarker for disease severity and mortality in COVID-19 patients

COVID-19, caused by SARS-CoV-2, is a contagious life-threatening viral disease that has killed more than three million people worldwide to date. Attempts have been made to identify biomarker(s) to stratify disease severity and improve treatment and resource allocation. Patients with SARS-COV-2 infection manifest with a higher inflammatory response and platelet hyperreactivity; this raises the question of the role of thrombopoiesis in COVID-19 infection. Immature platelet fraction (IPF, %) and immature platelet counts (IPC, x10(9)/l) can be used to assess thrombopoiesis. This study investigates whether the level of thrombopoiesis correlates with COVID-19 severity. A large cohort of 678 well-characterized COVID-19 patients was analyzed, including 658 (97%) hospitalized and 139 (21%) admitted to the intensive care unit (ICU). Elevated percentage IPF at presentation was predictive of length of hospitalization (P < 0 center dot 01) and ICU admission (P < 0 center dot 05). Additionally, percentage IPF at the peak was significantly higher among ICU patients than non-ICU patients (6 center dot 9 +/- 5 center dot 1 vs 5 center dot 3 +/- 8 center dot 4, P < 0 center dot 01) and among deceased patients than recovered patients (7 center dot 9 +/- 6 center dot 3 vs 5 center dot 4 +/- 7 center dot 8, P < 0 center dot 01). Furthermore, IPC at the peak was significantly higher among ICU patients than non-ICU patients (18 center dot 5 +/- 16 center dot 2 vs. 13 center dot 2 +/- 8 center dot 3, P < 0 center dot 05) and among patients on a ventilator than those not (22 center dot 1 +/- 20 center dot 1 vs.13 center dot 4 +/- 8 center dot 4, P < 0 center dot 05). Our study demonstrated that elevated initial and peak values of percentage IPF and IPC might serve as prognostic biomarkers for COVID-19 progression to severe conditions.