Abstract: ll Clinical Advances Outcomes of Hydroxychloroquine Usage in United States Veterans Hospitalized with COVID-19 Joseph Magagnoli, Siddharth Narendran, Felipe Pereira, Tammy H. Cummings, James W. Hardin, S. Scott Sutton, Jayakrishna Ambati sutton@cop.sc.edu (S.S.S.) ja9qr@virginia.edu (J.A.) HIGHLIGHTS Hydroxychloroquine (HC) use did not reduce the risk of ventilation or death HC with azithromycin (AZ) did not reduce the risk of ventilation or death HC, with or without AZ, was associated with longer length of hospital stay In this nationwide retrospective analysis of 807 patients hospitalized with COVID19, Magagnoli et al. report that, after adjusting for several COVID-19-relevant clinical and demographic characteristics, hydroxychloroquine use, with or without azithromycin, did not improve mortality or reduce the need for mechanical ventilation compared to no hydroxychloroquine use. Magagnoli et al., Med 1, 1–14 November 1, 2020 ª 2020 Elsevier Inc. https://doi.org/10.1016/j.medj.2020.06.001 Please cite this article in press as: Magagnoli et al., Outcomes of Hydroxychloroquine Usage in United States Veterans Hospitalized with COVID19, Med (2020), https://doi.org/10.1016/j.medj.2020.06.001 ll Clinical Advances Outcomes of Hydroxychloroquine Usage in United States Veterans Hospitalized with COVID-19 Joseph Magagnoli,1,2,8 Siddharth Narendran,4,5,8 Felipe Pereira,4,5,8 Tammy H. Cummings,1,2 James W. Hardin,1,3 S. Scott Sutton,1,2,* and Jayakrishna Ambati4,5,6,7,9,* SUMMARY Context and Significance Background: Despite limited and conflicting evidence, hydroxychloroquine, alone or in combination with azithromycin, is widely used in COVID-19 therapy. Methods: We performed a retrospective study of electronic health records of patients hospitalized with confirmed SARS-CoV-2 infection in US Veterans Health Administration medical centers between March 9, 2020 and April 29, 2020. Patients hospitalized within 24 h of diagnosis were classified based on their exposure to hydroxychloroquine alone (HC) or with azithromycin (HC+AZ) or no HC as treatments. The primary outcomes were mortality and use of mechanical ventilation. Findings: A total of 807 patients were evaluated. Compared to the no HC group, after propensity score adjustment for clinical characteristics, the risk of death from any cause was higher in the HC group (adjusted hazard ratio [aHR], 1.83; 95% confidence interval [CI], 1.16–2.89; p = 0.009), but not in the HC+AZ group (aHR, 1.31; 95% CI, 0.80–2.15; p = 0.28). Both the propensity-score-adjusted risks of mechanical ventilation and death after mechanical ventilation were not significantly different in the HC group (aHR, 1.19; 95% CI, 0.78–1.82; p = 0.42 and aHR, 2.11; 95% CI, 0.96–4.62; p = 0.06, respectively) or in the HC+AZ group (aHR, 1.09; 95% CI, 0.72–1.66; p = 0.69 and aHR, 1.25; 95% CI, 0.59–2.68; p = 0.56, respectively) compared to the no HC group. Conclusions: Among patients hospitalized with COVID-19, this retrospective study did not identify any significant reduction in mortality or in the need for mechanical ventilation with hydroxychloroquine treatment with or without azithromycin. Funding: University of Virginia Strategic Investment Fund Despite limited and conflicting evidence, hydroxychloroquine, with or without azithromycin, is extensively used to treat COVID19. Given the known side effects of these drugs, there is an urgent need to evaluate their effectiveness in COVID-19. In this nationwide retrospective..