Horby (2020)
Effect of Dexamethasone in Hospitalized Patients with COVID-19: Preliminary Report
Treatment for COVID-19 (Treated with dexamethasone vs. Usual care)
COVID-19 (severe/critical)
Risk ratio: 0.800 (0.700-0.920) Adjusted model

United Kingdom

Randomized clinical trial

Primary data collection


Randomized controlled trial of dexamethasone in patients hospitalized with COVID-19. The RECOVERY trial is an investigator-initiated, individually randomized, controlled, open-label, adaptive platform trial to evaluate the effects of potential treatments in patients hospitalized with COVID-19. The trial was conducted at 176 National Health Service (NHS) hospital organizations in the United Kingdom, supported by the National Institute for Health Research Clinical Research Network.

Of the 11,320 patients randomized between 19 March and 8 June, 9355 (83%) were eligible to be randomized to dexamethasone. Of these, 2104 were randomized to dexamethasone and 4321 were randomized to usual care, with the remainder being randomized to one of the other treatment arms. Mean age of study participants in this comparison was 66.1 years and 36% patients were female. A history of diabetes was present in 24% of patients, heart disease in 27%, and chronic lung disease in 21%, with 56% having at least one major comorbidity recorded. In this analysis, 82% of patients had laboratory confirmed SARS-CoV-2 infection, with the result currently awaited for 9%. At randomization, 16% were receiving invasive mechanical ventilation or extracorporeal membrane oxygenation, 60% were receiving oxygen only (with or without non-invasive ventilation), and 24% were receiving neither.


28 Day

COVID-19 (severe/critical)


Effect of allocation to dexamethasone on 28-day mortality by level of respiratory support received - "oxygen only" (n=3883) at randomization.


Treatment for COVID-19

The "oxygen only" group includes non-invasive ventilation. Effects in subgroups of level of respiratory support received were shown with 99% CIs, not 95% CIs as inadvertently stated. The age-adjusted rate ratio and 99% confidence intervals remain unchanged in this analysis.

Usual care



Treated with dexamethasone



Risk ratio

0.800 (0.700-0.920)




The estimates of rate ratios and risk ratios (both hereon denoted RR) were adjusted for baseline age.

dexamethasone reduced 28-day mortality among those receiving invasive mechanical ventilation or oxygen at randomization.