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Authors: Joseph Magagnoli, M.S. et al.

Link to paper:

Journal/ Pre-Print: medRxiv

Tags: Clinical, Statistics, Hydroxychloroquine, Azithromycin, Retrospective cohort analysis

Research Highlights 

1. Retrospectively analyse the effect of hydroxychloroquine (HCQ) +/- azithromycin (AZT)

2. Adjust the analysis with the information of comorbidities, medications, clinical and laboratory abnormalities


The research retrospectively analysed the data from hospitalised COVID-19 patients, categorising them into three groups: HCQ alone, with (AZT) and no exposure to HCQ . Using death and the need for mechanical ventilation as two major outcomes, it implies that HC does not show strong effect to mitigate COVID-19 related symptoms.

Impact for SARS-CoV2/COVID19 research efforts

While not conclusive, it summarises the efficacy of HC in COVID-19 treatment and suggest it to be less promising than previously assumed.

Study Type

Retrospective Clinical Cohort study 

Strengths and limitations of the paper

Novelty: Taking consideration of the effect of azithromycin.

Standing in the field:

It is still controversial whether HCQ is effective in the treatment of COVID-19. Though Chen et al. showed the shortening of TTCR by HCQ, a solid conclusion is still elusive and requires a strict, randomised clinical study in larger scale.

Appropriate statistics:

Low sample number; cases not randomised

Viral model used: N/A

Translatability: It may suggest less usefulness of HCQ in treatment of COVID-19

Main limitations: > Defects in subject selection and analysis: gender bias, no classification of severity of the subjects.

> Not strict clinical trial study but retrospective analysis; less indication for the drug application for the disease. > Poorly defined cohorts: some patients were treated with HCQ prior to ventilation and some post, despite ventilation being one of the primary outcomes measured

> Lack of control: patients that were treated with HCQ were more likely to already have suffer from more severe disease before treatment; in the ‘no treatment’ cohort approximately one third of patients were also treated with AZT, therefore making comparison between cohorts difficult.