Background Several observational studies have reported the rate of venous and arterial thrombotic events in patients infected with COVID-19, with conflicting results. The aim of this study was to estimate the rate of thrombotic and bleeding events in hospitalized patients diagnosed with Coronavirus disease 2019 (COVID-19). Methods This was a multicenter study of 636 patients admitted between 20 March 2020 and 31 May 2020 with confirmed COVID-19 in four hospitals. Results Over a median length of stay in the non-ICU group of 7 days and of 19 days in the ICU group, twelve patients were diagnosed with Venous thromboembolism (VTE) (1.8 %) (95 % CI, 1.1–3). The rate in the non-ICU group was 0.19 % (95 % CI, 0.04–0.84), and that in the ICU group was 10.3 % (95 % CI, 6.4–16.2). The overall rate of arterial event is 2.2 % (95 % CI, 1.4–3.3). The rates in the non-ICU and ICU groups were 0.94 % (95 % CI, 0.46–0.1.9) and 8.4 % (95 % CI, 5.0–14.0). The overall composite event rate was 2.9 % (95 % CI, 2.0–4.3). The composite event rates in the non-ICU and ICU groups were 0.94 % (95 % CI, 0.46–0.1.9) and 13.2 % (95 % CI, 8.7–19.5). The overall rate of bleeding is 1.7 % (95 % CI, 1.0–2.8). The bleeding rate in the non-ICU group was 0.19 % (95 % CI, 0.04–0.84), and that in the ICU group was 9.4 % (95 % CI, 5.7–15.1). The baseline D-dimer level was a significant risk factor for developing VTE (OR 1.31, 95 % CI, 1.08–1.57, p = 0.005) and composite events (OR 1.32, 95 % CI, 1.12–1.55, p = 0.0007). Conclusions In this study, we found that the VTE rates in hospitalized patients with COVID-19 might not be higher than expected. In contrast to the risk of VTE, we found a high rate of arterial and bleeding complications in patients admitted to the ICU. An elevated D-dimer level at baseline could predict thrombotic complications in COVID-19 patients and may assist in the identification of these patients. Given the high rate of bleeding, the current study suggests that the intensification of anticoagulation therapy in COVID-19 patients beyond the standard of care be pursued with caution and would best be evaluated in a randomized controlled study.

Background: Coronavirus disease 2019 (COVID-19) is a global pandemic with a substantial impact on mortality, the health system and the economy8,9. Several observational studies reported the rate of venous and arterial thrombotic events in patients infected with COVID-19, with conflicting results . The aim of this multicentre study was to estimate the rate of thrombotic and bleeding events in hospitalized patients diagnosed with COVID-19 in Saudi Arabia. Method: multicenter study of 636 hospitalized patients with COVID-19.Result: Twelve patients were diagnosed with VTE 1.89% (95% CI, 1.18–3). The rate in the non-ICU group was 0.19% (95% CI, 0.04–0.84) compared to 10.38% (95% CI, 6.45–16.27) in the ICU group. Fourteen patients were diagnosed with an arterial event with an overall rate of 2.20% (95% CI, 1.43–3.38). The rate in the non-ICU group was 0.94% (95% CI, 0.46–0.1.93) and 8.49% (95% CI, 5.01–14.04) in the ICU group. The overall composite events rate was 2.99% (95% CI, 2.06–4.31). The composite events rate in the non-ICU group was 0.94% (95% CI, 0.46–0.1.93) and 13.21% (95% CI, 8.7–19.54) in the ICU group. Eleven patients developed bleeding with an overall rate of 1.73% (95% CI, 1.06–2.81). The bleeding rate in the non-ICU group was 0.19% (95% CI, 0.04–0.84), and 9.43% (95% CI, 5.72–15.16) in the ICU group. Of the selected risk factors, the only risk factor that predicted VTE and the composite outcome, was the baseline D-dimer. (OR 1.31, 95% CI, 1.084-1.573, p=0.005) and composite events (OR 1.32, 95% CI, 1.126-1.555, p=0.0007).Conclusion: Of 636 adults with COVID-19, the rate of VTE was similar to the rate of hospitalized patients with a similar degree of critical illness. In contrast to the risk of VTE, we found a high rate of arterial and bleeding complications in patients admitted to ICU. An elevated D-dimer at baseline could predict a thrombotic complication in the COVID-19 patients, which may assist in the identification of these patients. Given the high rate of bleeding, the current study suggests that the intensification of anticoagulation in COVID-19 patients beyond the standard of care, should be pursued with caution and is best evaluated in a randomised controlled study.