Ivermectin fails to lower incidence of hospitalization in large COVID-19 study
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Ivermectin did not lower the incidence of hospitalization among high-risk adults with COVID-19 enrolled in a large double-blind, randomized, placebo-controlled trial in Brazil, researchers reported in The New England Journal of Medicine.
The researchers said the trial of more than 3,500 patients will have a significant impact on the body of evidence for ivermectin as a potential therapy for COVID-19, which has generated a lot of controversy.
WHO, the FDA and the Infectious Diseases Society of America all recommend against its use.
“The evidence supporting the role of ivermectin in the treatment of COVID-19 is inconsistent. At least three meta-analyses of ivermectin trials have strongly indicated a treatment benefit, and others have concluded that there was no benefit,” Gilmar Reis, MD, PhD, and colleagues from the Together trial wrote.
“Although the number of included trials involving outpatients varies among the meta-analyses, the overall number of events that occurred in our trial is larger than the number of all the combined events in these meta-analyses. The results of this trial will, therefore, reduce the effect size of the meta-analyses that have indicated any benefits,” they wrote.
They noted that identifying “inexpensive, widely available, and effective therapies against COVID-19 is of great importance.”
“The repurposing of existing medicines that are widely available and that have reasonably well understood safety profiles has appeal,” they wrote. “One drug that has received considerable public use and interest is ivermectin, which is typically used as an antiparasitic drug.”
According to the researchers, more than 60 randomized trials of ivermectin as a treatment for COVID-19 have been registered, with findings being reported for more than 30. However, the results have been “discordant, and various review groups interpret the evidence differently — some advocating for benefits of ivermectin, and others reticent to conclude a benefit. Most of the trials have been small, with several being withdrawn from publication over credibility concerns.
Reis and colleagues evaluated ivermectin for the prevention of COVID-19 hospitalization among outpatients infected with SARS-CoV-2 at 12 public health clinics in Minas Gerais, Brazil. They randomly assigned 3,515 high-risk patients who had COVID-19 symptoms for up to a week to receive either ivermectin once daily for 3 days (n = 679 patients), placebo (n = 679), or another intervention (n = 2,157).
Overall, 100 patients (14.7%) in the ivermectin group had a primary outcome event — which researchers described as hospitalization due to COVID-19 within 28 days after randomization or an ED visit due to clinical worsening of COVID-19 — compared with 111 (16.3%) in the placebo group (RR = 0.9; 95%, Bayesian credible interval, 0.7-1.16). Of the 211 primary outcome events, 171 (81%) were hospital admissions.
According to the study, the findings were similar to the primary analysis in a modified intention-to-treat analysis that included only patients who received at least one dose of ivermectin or placebo (RR = 0.89; 95% Bayesian credible interval, 0.69-1.15) and in a per-protocol analysis that included only patients who reported 100% adherence to the assigned regimen (RR = 0.94; 95% Bayesian credible interval, 0.67-1.35).
The researchers noted that WHO has concluded, based on past trial results, that there exists “only very-low-certainty evidence regarding ivermectin” and recommended against its use for the treatment of patients with COVID-19 outside of clinical trials, as the IDSA also has done.
The FDA has warned that data do not show that ivermectin is effective against COVID-19 and that taking large doses of it is dangerous.
“The findings in our trial are consistent with these conclusions,” Reis and colleagues wrote.
References:
FDA. Why you should not use ivermectin to treat or prevent COVID-19. https://www.fda.gov/consumers/consumer-updates/why-you-should-not-use-ivermectin-treat-or-prevent-covid-19. Accessed on March 31, 2022.
IDSA. Guidelines on the treatment and management of patients with COVID-19. https://www.idsociety.org/practice-guideline/covid-19-guideline-treatment-and-management/#toc-17. Accessed on March 31, 2022.
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