The anti-malarial treatments chloroquine and hydroxychloroquine do not provide benefit to Covid-19 patients, according to researchers from the US and Switzerland.
In fact, their study found the use of chloroquine or hydroxychloroquine was linked to increased rates of mortality and heart arrhythmias among hospital patients with Covid-19.
“We suggest these drugs should not be used as treatments for Covid-19 outside of clinical trials”
As a result, they recommended that the drug regimens should not be used to treat Covid-19 outside of clinical trials.
Chloroquine is an antimalarial drug and its analogue, hydroxychloroquine, is used to treat autoimmune diseases including lupus and arthritis. Both drugs have a good safety profile.
The large observational study appears to have dashed hopes that the treatments would prove to be effective against coronavirus, after they were shown to have antiviral effects in laboratory tests.
The findings, published on Friday in The Lancet, prompted the World Health Organization on Monday to temporarily suspend trials of hydroxychloriquine as a potential treatment for Covid-19.
Hydroxychloroquine’s use against Covid-19 has already been championed by US president Donald Trump and the Brazilian government, as well as being permitted in France and India.
But the new study suggested that treatment with chloroquine or its analogue hydroxychloroquine – taken with or without the macrolide antibiotics azithromycin or clarithromycin – offered no benefit.
Researchers analysed data from nearly 15,000 patients with Covid-19 receiving a combination of any of the four drug regimens and 81,000 controls.
Meanwhile, treatment among patients with Covid-19, either alone or in combination with the macrolide antibiotics, was linked to an increased risk of serious heart rhythm complications.
In the study, researchers analysed data from 96,032 patients admitted between 20 December 2019 and 14 April 2020 with laboratory confirmed Covid-19 from 671 hospitals.
All of the patients included in the study had either been discharged or had died by 21 April 2020.
The authors compared outcomes from patients treated with chloroquine alone, hydroxychloroquine alone, chloroquine in combination with a macrolide or hydroxychloroquine with a macrolide.
Patients from these four groups were compared with the remaining control group of 81,144 patients.
At the end of the study period, around one in 11 patients in the control group had died in hospital. All four of the treatments were associated with a higher risk of dying in hospital.
“We now know from our study that the chance that these medications improve outcomes in Covid-19 is quite low”
Of those treated with chloroquine or hydroxychloroquine alone, around one in six patients had died, said the researchers.
When the drugs were used in combination with a macrolide, the death rate rose to more than one in five for chloroquine and almost one in four for hydroxychloroquine.
The team also found that serious cardiac arrhythmias were more common in the groups receiving either of the four treatment regimens.
The biggest increase was seen in the group treated with hydroxychloroquine in combination with a macrolide, where 8% of patients developed a heart arrhythmia compared with 0.3% of controls.
Study co-author Professor Frank Ruschitzka, director of the Heart Center at University Hospital Zurich, said: “Several countries have advocated use of chloroquine and hydroxychloroquine.”
He noted that “justification for repurposing these medicines” was based on a small number of “anecdotal experiences” suggesting they may have beneficial effects for coronavirus patients.
“However, we now know from our study that the chance that these medications improve outcomes in Covid-19 is quite low,” he said.
Lead study author Professor Mandeep Mehra, executive director of the Brigham and Women’s Hospital Center for Advanced Heart Disease in Boston, agreed.
“This is the first large scale study to find statistically robust evidence that treatment with chloroquine or hydroxychloroquine does not benefit patients with Covid-19,” he said.
“Instead, our findings suggest it may be associated with an increased risk of serious heart problems and increased risk of death.”
He added: “We suggest these drugs should not be used as treatments for Covid-19 outside of clinical trials.”