“The hype around ivermectin is driven by some studies where the
effect size for ivermectin is frankly not credible,” Paul Garner, the coordinating editor of the Cochrane Infectious Diseases Group, says in a statement. “Careful appraisal is the cornerstone of Cochrane’s work, and with such extreme public demands for a drug to work during the pandemic, it remains vital that we hold onto our scientific principles to guide care.”
The team’s final analysis included 14 randomized controlled trials with a total of 1,678 adults. Six of the studies were double-blinded and placebo-controlled—factors considered to improve the quality of evidence in drug trials. Nine of the 14 studies focused on moderate COVID-19 cases in hospital settings, four on mild cases in outpatients, and one on the use of ivermectin as a preventive medicine.
The team
identified an additional 38 studies that failed to meet the review’s inclusion criteria, mainly because they contained problematic comparisons or data, or otherwise didn’t meet scientific standards for strong evidence. For example,
nearly a third of the studies evaluated ivermectin alongside other treatments that varied between different groups of patients, making it difficult to extract the effect of ivermectin, specifically, from the data.
Several studies classified people as COVID-19 patients without testing to make sure they had the disease with a PCR or antigen test.
One of the excluded studies, a widely cited paper first posted late last year on the preprint server Research Square, was withdrawn a couple weeks ago following
allegations of data manipulation. The study, led by researchers in Egypt, claimed to have found a dramatic effect of ivermectin treatment on COVID-19 outcomes. However,
researchers identified multiple inconsistencies in the data, The Guardian reported in July, particularly regarding the numbers of patients and their dates of hospital admission.
One patient was even reported to have left the hospital on the “non-existent date of 31/06/2020,” Jack Lawrence, a medical student in London who identified problems in the paper, tells The Guardian.
Another study that was not included in the Cochrane review, this one carried out in Argentina, has come under increased scrutiny from scientists in the last few days after epidemiologist and blogger Gideon Meyerowitz-Katz documented multiple inconsistencies—including
numbers of patients that don’t add up and implausible effect sizes—on Twitter. “
As far as interventional observational trials go, this is probably the worst one I’ve ever seen,” he writes.