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A large observational study suggests that treatment with the antimalarial drug chloroquine or its analog, hydroxychloroquine (taken with or without the antibiotics azithromycin or clarithromycin), offers no benefit Covid-19 patients. The study analyzed data from nearly 15,000 Covid-19 patients who received a combination of any of the four drug regimens and 81,000 controls.

It is the medicine that the President of the United States, Donald Trump, has assured that he has been taking for more than a week, despite having no symptoms, because he has heard “many good things” about its effect. “I am taking it, hydroxychloroquine. I started taking it a couple of weeks ago. It will not harm me,” he said.

Furthermore, research has shown that treatment with these drugs among Covid-19 patients, either alone or in combination with macrolide antibiotics, is related to a increased risk of serious complications heart rate in these patients.

The researchers suggest that these treatment regimens should not be used to treat Covid-19 outside of clinical trials until the results of randomized clinical trials are available to confirm the safety and efficacy of these drugs for patients with Covid-19.

Chloroquine is an antimalarial drug and its analog, hydroxychloroquine, is used to treat autoimmune diseases such as lupus and arthritis. Both drugs have a good safety profile as treatments for those specific conditions, and the results do not imply that patients should stop taking these drugs if they are prescribed for approved conditions. They have also been shown to have antiviral effects in laboratory tests and are therefore of interest as possible treatments for Covid-19.

“This is the first large-scale study that finds statistically sound evidence that chloroquine or hydroxychloroquine treatment does not benefit patients with Covid-19. Instead, our findings suggest that it may be associated with an increased risk of serious heart problems and an increased risk of death. Randomized clinical trials are essential to confirm any harm or benefit associated with these agents. In the meantime, we suggest that these drugs should not be used as treatments for Covid-19 outside of clinical trials, “explains Mandeep R. Mehra, lead author of the study and executive director of the Center for Advanced Heart Disease at Boston Brigham and Women’s Hospital ( United States).

In the study, researchers analyzed data from 96,032 patients hospitalized between December 20, 2019 and April 14, 2020 with laboratory-confirmed SARS-CoV-2 infection in 671 hospitals. All the patients included in the study had been discharged or died as of April 21, 2020.

The team compared patient outcomes treated with chloroquine alone (1,868), hydroxychloroquine alone (3,016), chloroquine in combination with a macrolide (3,783), or hydroxychloroquine with a macrolide (6,221). Patients in these four groups were compared to the remaining control group of 81,144 patients.

At the end of the study period, about one in 11 patients in the control group had died in hospital (9.3%, 7,530 / 81,144). The four treatments were associated with a increased risk of dying in hospital. Of those treated with chloroquine or hydroxychloroquine alone, about one in six patients had died (16.4%, 307 / 1,868 chloroquine and 18.0%, 543 / 3,016 hydroxychloroquine). When the drugs were used in combination with a macrolide, the mortality rate increased to more than one in five in the case of chloroquine (22.2%, 839/3,783) and almost one in four in that of hydroxychloroquine. (23.8%, 1,479 / 6,221).

Part of the difference in mortality rates is due to underlying differences between patients who received the treatments and those who did not. After taking into account factors such as age, race, body mass index and health conditions researchers, such as heart disease, lung disease, and diabetes, found that drug regimens were associated with an increased risk of death.

They estimated that the excess risk attributable to the use of the drug regimen instead of other factors Like comorbidities, it ranged from 34 to 45%. The authors explain that if the mortality rate is 9.3% in the control group, after adjusting for the other clinical factors, the rate attributable to the use of drug regimens would rise to 12.4-13.4%. However, the researchers caution that it is not possible to exclude the possibility that other unmeasured factors are responsible for the apparent relationship between treatment with these drugs and decreased patient survival, as such is the design of the studies. of observation, and randomized trials are urgently needed.

The team also found that severe cardiac arrhythmias, which cause the lower chamber of the heart to beat rapidly and irregularly, were more common in groups receiving any of the four treatment regimens.

The greatest increase was observed in the group treated withhydroxychloroquine in combination with a macrolide, in which 8% of patients developed cardiac arrhythmia (502 / 6,221) compared to 0.3% of patients in the control group (226/81144). Taking into account demographic factors and pre-existing conditions, the team calculated that treatment with this drug combination is associated with a more than five-fold increase in the risk of developing severe cardiac arrhythmia while in the hospital (for example , an increase from 0.3% to 1.5% would be attributable to the medication regimen after adjustment for other clinical factors).

Similarly, it is not possible to conclusively infer the cause and effect between treatment with these medications and the occurrence of cardiac arrhythmias. It will be necessary conduct randomized clinical trials before reaching a conclusion about the benefit or harm of these agents in patients with Covid-19.