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Observational Study of Hydroxychloroquine in Hospitalized Patients with COVID-19

Our take —

In this observational study of hydroxychloroquine treatment, researchers found no significant association between hydroxychloroquine and intubation or death. These results suggest that hydroxychloroquine may not be beneficial or harmful to COVID-19 patients, or, even if it may be beneficial or harmful, the amount of benefit or harm is likely to be modest. Randomized controlled trials are needed to definitively assess the efficacy of hydroxychloroquine for COVID-19.

Study design

Prospective Cohort Study

Study population and setting

This study included 1376 adults admitted to New York–Presbyterian Hospital (NYP)–Columbia University Irving Medical Center (CUIMC) who had any positive SARS-CoV-2 test during admission from March 7 to April 8, 2020. Exclusion criteria included intubation, death, or transfer within 24 hours of admission. 811 (58.9%) patients received hydroxychloroquine. A multivariable cox model with inverse probability weighting according to the propensity score was used to assess the primary outcome (a composite of intubation or death) in patients who received hydroxychloroquine compared to patients who did not.

Summary of Main Findings

Hydroxychloroquine was not significantly associated with intubation or death (hazard ratio, 1.04, 95% CI: 0.82 to 1.32). Multiple sensitivity analyses found similar results.

Study Strengths

This study had a relatively large sample size compared to other hydroxychloroquine studies, adjustment for confounding variables including comorbidities known to increase risk of poor prognosis in COVID-19.


Participants were not randomized to treatment groups. The study occurred in a single academic hospital center in an urban location, and may not be applicable in other settings. Missing data for some variables and potential for inaccuracies in the electronic health records may bias results. Residual confounding remains possible.

Value added

This was a relatively large observational study on the clinical utility of hydroxycholoroquine with rigorous adjustment for confounding.