key: cord-0938662-l7zxvgnr
authors: Brito-Azevedo, Anderson
title: Hydroxychloroquine in COVID-19: taking care of statistic to take care of patients
date: 2020-08-06
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2020.07.079
sha: e551e96079ab3bb7f6c72aa1e03a9db20c6ff3d0
doc_id: 938662
cord_uid: l7zxvgnr

nan

Dear editor, I read with great interest the article published by Arshad and Henry Ford COVID-19 Task Force. They evaluated the role of hydroxychloroquine (HCQ) therapy alone and in combination with azithromycin in hospitalized COVID-19 patients.

They included a total of 2.541 patients divided in four groups: HCQ alone, HCQ+azithromycin, azithromycin alone, and neither drug. The authors performed propensity score matching to control confounding factors, using the parameters included in the Cox regression model. They observed a lowest mortality in 'HCQ alone' group when comparing to HCQ+azithromycin, azithromycin alone, and neither drug group [1] .

However, there are some aspects that should be considered. Firstly, patients with severe COVID-19 and with minimal cardiac risk factors were selected to be included in HCQ+azithromycin group. This criterion probably conferred a priori selection bias, turning difficult the further correction during statistical analysis.

Moreover, the median age (an important and well-known risk factor) was lowest in HCQ alone group.

Secondly, the authors adopted mSOFA score and O2 saturation in admission, as prognostic factors. However, 25% of the population did not have mSOFA score available, contributing to increase potential bias. Nevertheless, mSOFA comparison raised serious concern about bias in this study, since mSOFA mean was significant lower in 'HCQ alone' than in other groups. This point could be probably corrected by propensity matching. However, it is well known that validation of a propensity matching depends of the variables included in model. The COVID-19 pandemic promoted an increase in number of evidences in a considered short time. However, a race to a 'silver bullet' must not compromise the science and the evidence-based medicine.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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