Observational Study of Hydroxychloroquine for COVID-19

Quick Takes

  • Hydroxychloroquine has been discussed broadly as a potential treatment for COVID-19.
  • In a large, single-center, observational study of ~1,400 patients hospitalized with COVID-19, use of hydroxychloroquine did not reduce the risk of intubation or death.
  • Use of hydroxychloroquine for treatment of COVID-19 should primarily be limited to clinical trial settings to appropriately examine potential benefits and harms.

Study Questions:

What is the association between hydroxychloroquine use and intubation or death for patients hospitalized with COVID-19?


Consecutive patients with COVID-19 who were hospitalized at a single academic medical center in New York City between May 7 and April 8, 2020 were enrolled. Patients were excluded if they were intubated, died, or discharged within 24 hours of emergency department presentation. The primary endpoint was a composite of intubation or death with follow-up through April 25, 2020. The study used a time-to-event analysis comparing patients who did and did not receive hydroxychloroquine. Statistical methods included multivariable Cox model with inverse probability weighting according to a propensity score.


Of the 1,446 consecutive patients with COVID-19 admitted to this hospital, 1,376 were included in the analysis with a median follow-up of 22.5 days. Of the included patients, 811 (58.9%) received hydroxychloroquine for a median of 5 days; treatment was initiated within 48 hours of emergency department arrival in 85.9% of cases. Patient receiving hydroxychloroquine were more ill at baseline. Overall, 346 (25.1%) patients experienced the primary endpoint. In the multivariable model, there was no significant association between hydroxychloroquine use and risk of intubation or death (hazard ratio, 1.04; 95% confidence interval, 0.82-1.32). Similar results were seen using other propensity-score analysis methods.


The authors concluded that use of hydroxychloroquine was not associated with a lower risk of intubation or death among patients hospitalized for COVID-19 in this single-center, observational study.


Since the beginning of this pandemic, significant interest has developed in both the medical and lay communities about the potential role of hydroxychloroquine to treat COVID-19. This included an emergency use authorization from the Food and Drug Administration (FDA) on March 30, 2020, to use hydroxychloroquine to treat COVID-19 in nonclinical trial settings. Early reports suggested potential benefit, but were limited by small sample sizes, early termination due to side effects (e.g., prolongation of QT interval), or had not been formally peer reviewed. This retrospective, single-center study is the largest to date to report on the association between hydroxychloroquine use and clinical outcomes. While the data do not find any benefit (or harm) associated with hydroxychloroquine use, the authors acknowledge the limitations of an observational, single-center study design with missing data and potential inaccuracies in electronic health record data collection. As the authors note, a well-conducted, prospective randomized trial is needed to accurately assess the potential benefit and quantify potential harms with hydroxychloroquine use for COVID-19. Routine use of hydroxychloroquine for treating COVID-19 is not recommended outside of a clinical trial context based on the lack of efficacy identified to date and the known potential harms.

Clinical Topics: Arrhythmias and Clinical EP, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Novel Agents, Statins

Keywords: Arrhythmias, Cardiac, Coronavirus, COVID-19, Emergency Service, Hospital, Hydroxychloroquine, Intubation, Intratracheal, Patient Discharge, Primary Prevention, severe acute respiratory syndrome coronavirus 2

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