血栓性合併症を有した重症 COVID-19 患者の臨床的特徴（第 1 波〜第 3 波・後ろ向き観察研究）

Background and Objectives: Patients with coronavirus disease 2019 (COVID-19) are at increased risk of thrombosis. However, basic epidemiological information in the Japanese population is limited. Therefore, the purpose of this study was to assess the incidence of thromboembolic complications, the characteristics of patient background, and the outcomes of patients with severe COVID-19 during the first to the third waves of the pandemic. Methods: We conducted a retrospective observational study of all patients who had COVID-19, as confirmed with reverse transcriptase polymerase chain reaction testing, and had been admitted to the intensive care unit (ICU) from January 1, 2020, to March 31, 2021. Patient background, thrombotic complications, and clinical outcomes were described. Results: A total of 42 patients had been admitted to the ICU. The reason for ICU admission was acute respiratory failure for 90% of patients. The median length of stay in the ICU was 11.5 days, and the median length of stay in the hospital was 29.5 days. A total of 14 thromboembolic complications occurred in 9 of 42 (21%) patients. Thromboembolic complications included 1 case of descending aortic thrombosis, 2 cases of cerebral infarction, 6 cases of deep vein thrombosis, and 5 cases of pulmonary thromboembolism. Of the 42 patients, 23 (55%) were discharged home; 7 (17%) were transferred to another hospital, 8 (19%) died in the ICU, and 4 (10%) died in wards. The mortality rates in the ICU and in the hospital were significantly higher for patients with thromboembolic complications than for other patients. Conclusions: In critically ill patients with COVID-19, the incidence of thromboembolic complications is high. These finding suggest a more-focused assessment on thrombotic complications is vital when caring for patients with COVID-19.