In hospitalized patients with coronavirus disease 2019 (COVID-19), ivermectin was associated with lower mortality compared to treatment without the antiparasitic drug, according to study results published in CHEST.

Researchers reviewed charts of 280 consecutive patients who were hospitalized at 4 hospitals in Florida with confirmed COVID-19 between March 15 and May 11, 2020. A total of 173 patients in this cohort were treated with ivermectin vs 107 who were not treated with ivermectin. Dosing of ivermectin was per treating physician’s discretion. The majority of patients in both groups received hydroxychloroquine (92.9%) and azithromycin (86.7%).

The primary outcome of the study was all-cause in-hospital mortality. Secondary outcomes included mortality in patients with severe pulmonary involvement, extubation rates for mechanically ventilated patients, and hospital length of stay (LOS). The investigators defined severe pulmonary involvement as the need for 50% or more of fraction of inspired oxygen (FiO2), high-flow nasal oxygen, noninvasive ventilation, or intubation and mechanical ventilation at study entry.

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In the multivariable-adjusted analysis, mortality was significantly lower in patients treated with ivermectin compared with those not treated with the drug (odds ratio [OR], 0.27; 95% CI, 0.09-0.80; P =.03). Of the 196 patients in the propensity-matched cohort, mortality remained significantly lower in patients treated with ivermectin (13.3% vs 24.5%; OR, 0.47; 95% CI, 0.22-0.99; P =.045).

Mortality rates were significantly lower in a subgroup of patients with pulmonary involvement who were treated with ivermectin compared with similar patients not treated with the drug (38.8% vs 80.7%, respectively; OR, 0.15; 95% CI, 0.05-0.47; P =.001). No differences were found in the unmatched and matched cohorts with regard to the median hospital LOS and extubation rates.

A limitation of this study included its retrospective design. Additionally, the inclusion of a large proportion of patients who were also receiving concomitant medications, such as hydroxychloroquine and azithromycin, may have limited the ability to determine whether ivermectin itself was responsible for the observed mortality benefits.

The investigators concluded that “further studies in appropriately designed randomized trials are recommended before any conclusions can be made,” including appropriate dosing for hospitalized patients with COVID-19.


Rajter JC, Sherman MS, Fatteh N, Vogel F, Sacks J, Rajter J-J. Use of ivermectin is associated with lower mortality in hospitalized patients with COVID-19 (ICON study). Published online October 12, 2020. CHEST. doi:10.1016/j.chest.2020.10.009