Of the 1107 patients who were assessed for eligibility, 1063 underwent randomization; 541 were assigned to the remdesivir group and 522 to the placebo group (Figure 1). Of those assigned to receive remdesivir, 531 patients (98.2%) received the treatment as assigned. Forty-nine patients had remdesivir treatment discontinued before day 10 because of an adverse event or a serious adverse event other than death (36 patients) or because the patient withdrew consent (13). Of those assigned to receive placebo, 518 patients (99.2%) received placebo as assigned. Fifty-three patients discontinued placebo before day 10 because of an adverse event or a serious adverse event other than death (36 patients), because the patient withdrew consent (15), or because the patient was found to be ineligible for trial enrollment (2).
As of April 28, 2020, a total of 391 patients in the remdesivir group and 340 in the placebo group had completed the trial through day 29, recovered, or died. Eight patients who received remdesivir and 9 who received placebo terminated their participation in the trial before day 29. There were 132 patients in the remdesivir group and 169 in the placebo group who had not recovered and had not completed the day 29 follow-up visit. The analysis population included 1059 patients for whom we have at least some postbaseline data available (538 in the remdesivir group and 521 in the placebo group). Four of the 1063 patients were not included in the primary analysis because no postbaseline data were available at the time of the database freeze.
The mean age of patients was 58.9 years, and 64.3% were male (Table 1). On the basis of the evolving epidemiology of Covid-19 during the trial, 79.8% of patients were enrolled at sites in North America, 15.3% in Europe, and 4.9% in Asia (Table S1). Overall, 53.2% of the patients were white, 20.6% were black, 12.6% were Asian, and 13.6% were designated as other or not reported; 249 (23.4%) were Hispanic or Latino. Most patients had either one (27.0%) or two or more (52.1%) of the prespecified coexisting conditions at enrollment, most commonly hypertension (49.6%), obesity (37.0%), and type 2 diabetes mellitus (29.7%).
The median number of days between symptom onset and randomization was 9 (interquartile range, 6 to 12). Nine hundred forty-three (88.7%) patients had severe disease at enrollment as defined in the Supplementary Appendix; 272 (25.6%) patients met category 7 criteria on the ordinal scale, 197 (18.5%) category 6, 421 (39.6%) category 5, and 127 (11.9%) category 4. There were 46 (4.3%) patients who had missing ordinal scale data at enrollment. No substantial imbalances in baseline characteristics were observed between the remdesivir group and the placebo group.
Cumulative recovery estimates are shown in the overall population (Panel A), in patients with a baseline score of 4 on the ordinal scale (not receiving oxygen; Panel B), in those with a baseline score of 5 (receiving oxygen; Panel C), in those with a baseline score of 6 (receiving high-flow oxygen or noninvasive mechanical ventilation; Panel D), and in those with a baseline score of 7 (receiving mechanical ventilation or ECMO; Panel E).
The widths of the confidence intervals have not been adjusted for multiplicity and therefore cannot be used to infer treatment effects. Race and ethnic group were reported by the patients.
Patients in the remdesivir group had a shorter time to recovery than patients in the placebo group (median, 11 days, as compared with 15 days; rate ratio for recovery, 1.32; 95% confidence interval [CI], 1.12 to 1.55; P<0.001; 1059 patients (Figure 2 and Table 2). Among patients with a baseline ordinal score of 5 (421 patients), the rate ratio for recovery was 1.47 (95% CI, 1.17 to 1.84); among patients with a baseline score of 4 (127 patients) and those with a baseline score of 6 (197 patients), the rate ratio estimates for recovery were 1.38 (95% CI, 0.94 to 2.03) and 1.20 (95% CI, 0.79 to 1.81), respectively. For those receiving mechanical ventilation or ECMO at enrollment (baseline ordinal scores of 7; 272 patients), the rate ratio for recovery was 0.95 (95% CI, 0.64 to 1.42). A test of interaction of treatment with baseline score on the ordinal scale was not significant. An analysis adjusting for baseline ordinal score as a stratification variable was conducted to evaluate the overall effect (of the percentage of patients in each ordinal score category at baseline) on the primary outcome. This adjusted analysis produced a similar treatment-effect estimate (rate ratio for recovery, 1.31; 95% CI, 1.12 to 1.54; 1017 patients). Table S2 in the Supplementary Appendix shows results according to the baseline severity stratum of mild-to-moderate as compared with severe. Patients who underwent randomization during the first 10 days after the onset of symptoms had a rate ratio for recovery of 1.28 (95% CI, 1.05 to 1.57; 664 patients), whereas patients who underwent randomization more than 10 days after the onset of symptoms had a rate ratio for recovery of 1.38 (95% CI, 1.05 to 1.81; 380 patients) (Figure 3).
Key Secondary Outcome
The odds of improvement in the ordinal scale score were higher in the remdesivir group, as determined by a proportional odds model at the day 15 visit, than in the placebo group (odds ratio for improvement, 1.50; 95% CI, 1.18 to 1.91; P=0.001; 844 patients) (Table 2 and Fig. S5). Mortality was numerically lower in the remdesivir group than in the placebo group, but the difference was not significant (hazard ratio for death, 0.70; 95% CI, 0.47 to 1.04; 1059 patients). The Kaplan–Meier estimates of mortality by 14 days were 7.1% and 11.9% in the remdesivir and placebo groups, respectively (Table 2). The Kaplan–Meier estimates of mortality by 28 days are not reported in this preliminary analysis, given the large number of patients that had yet to complete day 29 visits. An analysis with adjustment for baseline ordinal score as a stratification variable showed a hazard ratio for death of 0.74 (95% CI, 0.50 to 1.10).
Serious adverse events occurred in 114 patients (21.1%) in the remdesivir group and 141 patients (27.0%) in the placebo group (Table S3); 4 events (2 in each group) were judged by site investigators to be related to remdesivir or placebo. There were 28 serious respiratory failure adverse events in the remdesivir group (5.2% of patients) and 42 in the placebo group (8.0% of patients). Acute respiratory failure, hypotension, viral pneumonia, and acute kidney injury were slightly more common among patients in the placebo group. No deaths were considered to be related to treatment assignment, as judged by the site investigators.
Grade 3 or 4 adverse events occurred in 156 patients (28.8%) in the remdesivir group and in 172 in the placebo group (33.0%) (Table S4). The most common adverse events in the remdesivir group were anemia or decreased hemoglobin (43 events [7.9%], as compared with 47 [9.0%] in the placebo group); acute kidney injury, decreased estimated glomerular filtration rate or creatinine clearance, or increased blood creatinine (40 events [7.4%], as compared with 38 [7.3%]); pyrexia (27 events [5.0%], as compared with 17 [3.3%]); hyperglycemia or increased blood glucose level (22 events [4.1%], as compared with 17 [3.3%]); and increased aminotransferase levels including alanine aminotransferase, aspartate aminotransferase, or both (22 events [4.1%], as compared with 31 [5.9%]). Otherwise, the incidence of adverse events was not found to be significantly different between the remdesivir group and the placebo group.