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Observational Study
. 2020 May 14;369:m1844.
doi: 10.1136/bmj.m1844.

Clinical Efficacy of Hydroxychloroquine in Patients With covid-19 Pneumonia Who Require Oxygen: Observational Comparative Study Using Routine Care Data

Free PMC article
Observational Study

Clinical Efficacy of Hydroxychloroquine in Patients With covid-19 Pneumonia Who Require Oxygen: Observational Comparative Study Using Routine Care Data

Matthieu Mahévas et al. BMJ. .
Free PMC article


Objective: To assess the effectiveness of hydroxychloroquine in patients admitted to hospital with coronavirus disease 2019 (covid-19) pneumonia who require oxygen.

Design: Comparative observational study using data collected from routine care.

Setting: Four French tertiary care centres providing care to patients with covid-19 pneumonia between 12 March and 31 March 2020.

Participants: 181 patients aged 18-80 years with documented severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia who required oxygen but not intensive care.

Interventions: Hydroxychloroquine at a dose of 600 mg/day within 48 hours of admission to hospital (treatment group) versus standard care without hydroxychloroquine (control group).

Main outcome measures: The primary outcome was survival without transfer to the intensive care unit at day 21. Secondary outcomes were overall survival, survival without acute respiratory distress syndrome, weaning from oxygen, and discharge from hospital to home or rehabilitation (all at day 21). Analyses were adjusted for confounding factors by inverse probability of treatment weighting.

Results: In the main analysis, 84 patients who received hydroxychloroquine within 48 hours of admission to hospital (treatment group) were compared with 89 patients who did not receive hydroxychloroquine (control group). Eight additional patients received hydroxychloroquine more than 48 hours after admission. In the weighted analyses, the survival rate without transfer to the intensive care unit at day 21 was 76% in the treatment group and 75% in the control group (weighted hazard ratio 0.9, 95% confidence interval 0.4 to 2.1). Overall survival at day 21 was 89% in the treatment group and 91% in the control group (1.2, 0.4 to 3.3). Survival without acute respiratory distress syndrome at day 21 was 69% in the treatment group compared with 74% in the control group (1.3, 0.7 to 2.6). At day 21, 82% of patients in the treatment group had been weaned from oxygen compared with 76% in the control group (weighted risk ratio 1.1, 95% confidence interval 0.9 to 1.3). Eight patients in the treatment group (10%) experienced electrocardiographic modifications that required discontinuation of treatment.

Conclusions: Hydroxychloroquine has received worldwide attention as a potential treatment for covid-19 because of positive results from small studies. However, the results of this study do not support its use in patients admitted to hospital with covid-19 who require oxygen.

Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.


Fig 1
Fig 1
Study flowchart. Covid-19=coronavirus disease 2019; HCQ=hydroxychloroquine; ICU=intensive care unit
Fig 2
Fig 2
Kaplan-Meier curves for survival without transfer to intensive care in unweighted sample (top panel) and sample used for inverse probability of treatment weighting (bottom panel). A multivariable logistic regression model was constructed to estimate each patient’s probability of receiving hydroxychloroquine given their baseline covariates (that is, the propensity score: variables in model included age, sex, and comorbidities). ICU=intensive care unit

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