Change in platelet indices in patients with coronavirus infection disease (COVID-19): A reflection of platelet activation and contribution to immunothrombosis?

ABSTRACT

Background: Activation of the coagulation system, as reflected by raised D-dimers, is prevalent in patients with COVID-19 resulting in coagulopathies as well as venous and arterial macro-and microthromboses. Laboratory tests in patients admitted with COVID-19 should include prothrombin time (PT) and D-dimers. The role of platelets in COVID-19 related immunothrombosis has not been extensively documented. Aims: Investigate platelet indices in patients with COVID-19 with raised D-dimer levels and compare the results to COVID-19 infected patients with normal D-dimer levels as well as to COVID-19 uninfected patients with raised D-dimers. Methods: This retrospective observational study was approved by the Human Research Ethics Committee of the University of the Witwatersrand (M201010). The laboratory results of patients admitted to a quaternary referral centre in Johannesburg, South Africa from June to December 2020 were reviewed. Platelet indices including platelet large cell ratio (P-LCR), mean platelet volume (MPV) and platelet distribution width (PDW) were recorded and analysed in the following 3 cohorts 281 COVID-19 patients with raised D-dimers, 72 COVID-19 patients without raised D-dimers and 51 COVID-19 negative patients with raised D-dimers and disseminated intravascular coagulation (DIC). Results: The platelet indices P-LCR, MPV and PDW in COVID-19 positive patients were statistically different from patients without COVID-19 ( P < 0.001) (Table 1). No statistically significant difference in the platelet indices was however observed between COVID-19 patients with and without raised D-dimers. COVID-19, Corona virus disease-19;n , number of patients;SD, standard deviation;P-LCR, platelet large cell ratio;MPV, mean platelet volume;PDW, platelet distribution width. Conclusions: Platelet laboratory indices are statistically different between COVID-19 positive and COVID-19 negative patients but were not predictive of the presence of an underlying coagulopathy in COVID-19 as reflected by elevated D-dimer levels. The alterations in platelet indices in COVID-19 patients probably reflect activation of platelets and contribution to immunothrombosis.