The association of hemoglobin drop with in-hospital outcomes in COVID-19 patients

Background: Bleeding events can be critical in hospitalized patients with COVID-19, especially those with aggressive anticoagulation therapy. Aim: We aimed to investigate whether hemoglobin drop was associated with increased risk of acute kidney injury (AKI) and in-hospital mortality among patients with COVID-19. Design: Retrospective cohort study. Methods: This retrospective study was conducted by review of the medical records of 6683 patients with laboratoryconfirmed COVID-19 hospitalized in the Mount Sinai Health system between 1st March 2020 and 30th March 2021. We compared patients with and without hemoglobin drop >3 g/dl during hospitalization within a week after admissions, using inverse probability treatment weighted analysis (IPTW). Outcomes of interest were in-hospital mortality and AKI which was defined as serum creatine change of 0.3 mg/dl increase or 1.5 times baseline. Results: Of the 6683 patients admitted due to COVID-19, 750 (11.2%) patients presented with a marked hemoglobin drop. Patients with hemoglobin drop were more likely to receive therapeutic anticoagulation within 2 days after admissions. Patients with hemoglobin drop had higher crude in-hospital mortality (40.8% vs. 20.0%, P < 0.001) as well as AKI (51.4% vs. 23.9%, P < 0.001) compared to those without. IPTW analysis showed that hemoglobin drop was associated with higher inhospital mortality compared to those without (odds ratio (OR) [95% confidential interval (CO]: 2.21 [1.54-2.88], P <0.001) as well as AKI (OR [95% CI]: 2.79 [2.08-3.73], P <0.001). Conclusions: Hemoglobin drop during COVID-19 related hospitalizations was associated with a higher risk of AKI and in-hospital mortality.