Comorbidities and underlying conditions
The investigators conducted multiple analyses to control for confounding variables, including Cox proportional hazards regression and propensity score matching analyses.
“In an observational study, there is always a chance of residual confounding, which is why we did propensity score based matched analyses,” Dr. Ruschitzka explained.
No significant differences were found in distribution of demographics and comorbidities between the groups.
As good as it gets
“We found no benefit in any of the four treatment regimens for hospitalized patients with COVID-19, but we did notice higher rates of death and serious ventricular arrhythmias in these patients, compared to the controls,” Dr. Mehra reported.
Of the patients in the control group, roughly 9.3% died during their hospitalization, compared with 16.4% of patients treated with chloroquine alone, 18.0% of those treated with hydroxychloroquine alone, 22.2% of those treated with chloroquine and a macrolide, and 23.8% of those treated with hydroxychloroquine and a macrolide.
After accounting for confounding variables, the researchers estimated that the excess mortality risk attributable to use of the drug regimen ranged from 34% to 45%.
Patients treated with any of the four regimens sustained more serious arrhythmias, compared with those in the control group (0.35), with the biggest increase seen in the group treated with the combination of hydroxychloroquine plus a macrolide (8.1%), followed by chloroquine with a macrolide (6.5%), hydroxychloroquine alone (6.1%), and chloroquine alone (4.3%).
“We were fairly reassured that, although the study was observational, the signals were robust and consistent across all regions of the world in diverse populations, and we did not see any muting of that signal, depending on region,” Dr. Mehra said.
“Two months ago, we were all scratching our heads about how to treat patients with COVID-19, and then came a drug [hydroxychloroquine] with some anecdotal evidence, but now we have 2 months more experience, and we looked to science to provide some answer,” Dr. Ruschitzka said.
“Although this was not a randomized, controlled trial, so we do not have a definite answer, the data provided in this [large, multinational] real-world study is as good as it gets and the best data we have,” he concluded.
“Let the science speak for itself”
Commenting on the study in an interview, Christian Funck-Brentano, MD, from the Hospital Pitié-Salpêtrière and Sorbonne University, both in Paris, said that, although the study is observational and therefore not as reliable as a randomized controlled trial, it is “nevertheless well-documented, studied a huge amount of people, and utilized several sensitivity methods, all of which showed the same results.”
Dr. Funck-Brentano, who is the coauthor of anin The Lancet and was not involved with the study, said that “we now have no evidence that hydroxychloroquine and chloroquine alone or in combination with a macrolide do any good and we have potential evidence that they do harm and kill people.”
Also commenting on the study in an interview, David Holtgrave, PhD, dean of the School of Public Health at the State University of New York at Albany, said that, “while no one observational study alone would lead to a firm clinical recommendation, I think it is helpful for physicians and public health officials to be aware of the findings of the peer-reviewed observational studies to date and the National Institutes of Healthand concern about hydroxychloroquine to inform their decision-making as we await the results of randomized clinical trials of these drugs for the treatment of COVID-19,” said Dr. Holtgrave, who was not involved with the study.
He added that, to his knowledge, there are “still no published studies of prophylactic use of these drugs to prevent COVID-19.”
Dr. Mehra emphasized that a cardinal principle of practicing medicine is “first do no harm” and “even in situations where you believe a desperate disease calls for desperate measures, responsible physicians should take a step back and ask if we are doing harm, and until we can say we aren’t, I don’t think it’s wise to push something like this in the absence of good efficacy data.”
Dr. Ruschitzka added that those who are encouraging the use of these agents “should review their decision based on today’s data and let the science speak for itself.”
The study was supported by the William Harvey Distinguished Chair in Advanced Cardiovascular Medicine at Brigham and Women’s Hospital, Boston. Dr. Mehra reported personal fees from Abbott, Medtronic, Janssen, Mesoblast, Portola, Bayer, Baim Institute for Clinical Research, NuPulseCV, FineHeart, Leviticus, Roivant, and Triple Gene. Dr. Ruschitzka was paid for time spent as a committee member for clinical trials, advisory boards, other forms of consulting, and lectures or presentations; these payments were made directly to the University of Zürich and no personal payments were received in relation to these trials or other activities. Dr. Funck-Brentano, his coauthor, and Dr. Holtgrave declared no relevant financial relationships.
A version of this article originally appeared on.