Hematological manifestations of COVID-19 acute respiratory distress syndrome patients and the impact of thrombocytopenia on disease outcomes: A retrospective study.

Background: Platelet count is a simple and readily available biomarker, in which thrombocytopenia was shown to be independently associated with disease severity and risk of mortality in the critical coronavirus disease-19 (COVID-19) patients. The aim of this study was to investigate the impact of thrombocytopenia on disease progression in critically ill COVID-19 patients with acute respiratory distress syndrome (ARDS) admitted to a medical intensive care unit (ICU).

Methods: COVID-19-associated ARDS patients in our research hospitals' ICU were retrospectively investigated. Patients were divided into two groups as thrombocytopenic (<150 × 10⁹/ml) patients on admission or those who developed thrombocytopenia during ICU follow-up (Group 1) and those without thrombocytopenia during ICU course and follow-up (Group 2).

Results: The median platelet count of all patients was 240 × 10⁹/ml, and the median D-dimer was 1.16 mg/ml. On admission, 32 (18.3%) patients had thrombocytopenia. The mean platelet count of Group 1 was 100.0 ± 47.5 × 10⁹/ml. Group 1 was older and their Acute Physiology and Chronic Health Evaluation II and sequential organ failure assessment scores were higher. Group 1 had lower hemoglobin, neutrophil, and lymphocyte counts and higher ferritin and procalcitonin level. Invasive mechanical ventilation was more commonly needed, and disseminated intravascular coagulation (DIC) was more frequently observed in Group 1. The ICU and hospital length of stay of Group 1 was longer with higher mortality.

Conclusion: Patients with thrombocytopenia had increased inflammatory markers, frequency of DIC, duration of ICU stay, and mortality. The presence of thrombocytopenia may reflect the progression of COVID-19 toward an unfavorable outcome.