Paris (AFP)

The suppressor drug tocilizumab, used for rheumatoid arthritis, is not effective in treating patients with severe Covid-19, according to the results of a clinical trial published on Thursday.

This trial had to be stopped prematurely as a precaution because of a higher proportion of deaths in the patients who received this treatment, but this could not be attributed to the drug.

These results contradict other observational studies (no comparison had been made between patients receiving the treatment and others not receiving it) and therefore with a lower level of evidence.

They suggested that tocilizumab may be of benefit.

In early January, British Minister of Health Matt Hancock had relied on this type of study to announce that patients hospitalized in intensive care could receive tocilizumab.

The study published Thursday in the medical journal BMJ covers 129 patients hospitalized in Brazil, all in serious condition.

Sixty-five patients received tocilizumab in addition to standard care, and 64 did not, for comparison (this is called the "control group").

After 15 days, 28% of patients on tocilizumab were either placed on mechanical ventilation or died, compared to 20% in the other group.

In addition, 17% of patients on tocilizumab died from acute respiratory failure or from multiple organ failure, compared to 3% in the other group.

This difference prompted the researchers to stop the trial.

"Taking tocilizumab in addition to standard care was not effective in improving the clinical condition of patients at 15 days, and may increase mortality," conclude the study authors.

They point out, however, that the small number of patients included in this trial is an important limit to their work, which prevents a definitive conclusion from being drawn.

In addition, "the proportion of 3% of patients who died in the control group is abnormally low in seriously ill Covid patients", noted a scientist who did not participate in the study, Peter Horby, cited by the organization British Science Media Center.

"This low death rate could have been due to chance, which could have affected the results," continued Professor Horby of the University of Oxford.

This researcher is one of the managers of the large British Recovery trial, which evaluates the effectiveness of several treatments, including tocilizumab, but on a larger scale, on several thousand patients.

Researchers have been hoping for months that tocilizumab can fight the inflammatory phenomenon responsible for the most serious cases of Covid-19.

But so far studies have failed to provide a categorical answer.

© 2021 AFP