Introduction
Immune thrombocytopenia (ITP) is an autoimmune disease defined by a platelet count less than 100 × 109/L due to immune-mediated destruction of platelets with inadequate platelet production.1 ITP can occur as a primary in the absence of obvious underlying causes or as a secondary due to an underlying disease or a medication exposure. The majority of ITP patients are asymptomatic or present with mucocutaneous bleeding at the time of diagnosis. However, life-threatening bleeding can be the initial presentation, but still rare.2 Diagnosis of ITP is usually made clinically by excluding other causes of thrombocytopenia. Chronic ITP is characterized by persistent thrombocytopenia for 12 months or more.1
Several viral agents have been previously implicated as pathogenic triggers for secondary ITP.3 Since the identification of the novel coronavirus at the end of 2019, and thrombocytopenia was considered as a risk factor associated with poor COVID-19 outcomes.4 Several case reports and case series of ITP secondary to COVID-19 have been published5, 6, however, only two small-sized reports in the literature have reviewed the consequences of COVID-19 in patients previously diagnosed with chronic ITP.4, 7 For that reason, we designed a retrospective cohort study to investigate the clinical impacts of COVID-19 infection on the admitted patients to the hospital who previously diagnosed with chronic ITP.