Abstract: Journal of Global Antimicrobial Resistance 22 (2020) 842–844 Contents lists available at ScienceDirect Journal of Global Antimicrobial Resistance journal homepage: www.elsevier.com/locate/jgar Short Communication Hydroxychloroquine use in hospitalised patients with COVID-19: An observational matched cohort study Markos Kalligerosa,1, Fadi Shehadeha,1, Eleftheria Atallaa , Evangelia K. Mylonaa , Su Aunga , Aakriti Panditaa , Jerry Larkina , Martha Sancheza , Francine Touzard-Romoa , Amy Brothertonb , Rajeev Shahb , Cheston B. Cunhaa,**, Eleftherios Mylonakisa,* a b Infectious Diseases Division, Warren Alpert Medical School of Brown University, Providence, RI, USA Clinical Pharmacy, Lifespan, Providence, RI, USA A R T I C L E I N F O A B S T R A C T Article history: Received 24 June 2020 Received in revised form 13 July 2020 Accepted 27 July 2020 Available online 5 August 2020 Aim: To assess the efficacy and safety of hydroxychloroquine with or without azithromycin) in hospitalized adult patients with COVID-19. Methods: We utilized a hospital based prospective data registry. The primary end point was to assess the impact of hydroxychloroquine with or without azithromycin, on outcome, length of hospitalization, and time to clinical improvement. We utilized treatment effects with inverse-probability-weighting and Cox proportional hazards models. All analyses accounted for age, gender, race, severity on admission, days from symptoms onset and chronic comorbidities. Results: 36 patients received hydroxychloroquine and were age- and sex-matched to 72 patients with COVID-19 who received supportive care. Compared to supportive care, the use of HCQ did not shorten the time to clinical improvement (+0.23 days; 95% CI: 1.8–2.3 days) nor did it shorten the duration of hospital stay (+0.91 days; 95% CI: 1.1–2.9 days). Additionally, HCQ did not decrease the risk of COVID-19 in-hospital death (aHR 1.67; 95% CI: 0.29–9.36). Finally, we observed a slight QTc prolongation from a baseline of 444  26 ms to 464  32 ms (meanSD) among patients receiving hydroxychloroquine with or without azithromycin. Conclusion: This study did not yield benefits from hydroxychloroquine use in patients with COVID-19 and monitoring for adverse events is warranted. Nevertheless, the treatment was safely studied under the guidance of an antimicrobial stewardship program. © 2020 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/). Keywords: COVID-19 SARS-CoV-2 Hydroxychloroquine QTc Efficacy Safety Hydroxychloroquine (HCQ) and chloroquine were among the first drugs that emerged as potential therapeutic options against coronavirus disease 2019 (COVID-19). These two antimalarial drugs, also commonly used as immunomodulators in the setting of rheumatological diseases, showed in vitro activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [1,2]. The aim of this study was to assess the efficacy and safety of HCQ, with * Corresponding author. Present address: Infectious Diseases Division, Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy Street, POB, 3rd Floor, Suite 328/330, Providence, RI 02903, USA. ** Corresponding author. Present address: Antimicrobial Stewardship Program (Rhode Island Hospital & Miriam Hospital), Division of Infectious Disease,..