Due to the substantial morbidity but low rates of hospitalization and death among outpatients with COVID-19, symptom outcome measures should be considered for primary efficacy assessment in phase 3 treatment trials. We analyzed potential measures utilizing the ACTIV-2 participant diary.
Data from the first 95 participants in ACTIV-2 were included. All had symptomatic SARS-CoV-2 infection and received blinded bamlanivimab 7000 mg/placebo. The symptom diary was completed by participants prior to treatment (Day 0) and then daily for 28 days. It included 13 targeted symptoms scored as absent, mild, moderate, or severe, and a question about whether they had returned to pre-COVID-19 health. Without unblinding, 3 candidate symptom outcome measures were assessed: A) time to confirmed (2 consecutive days) absence of all targeted symptoms, B) time to all targeted symptoms confirmed to be mild or absent, and C) time to confirmed improvement in all targeted symptoms. Median time to outcome was estimated by Kaplan-Meier methods.
Of the 95 participants, 53% were female, 82% white, and 33% Latinx. Median age was 44 years; 46% were age ?55 years and/or had protocol-defined comorbidities. Median time from COVID-19 symptom onset to randomization was 6 days. Prevalence of each targeted symptom on Day 0 ranged from 6% vomiting to 87% fatigue. Candidate outcome B was met in median 2 days due to 29% of participants having only mild symptoms at Day 0. For candidate outcomes A and C, median time was 11 and 8 days, with 26% and 16%, respectively, not meeting the outcome by 28 days. These candidate outcomes (A and C) were associated with a participant’s confirmed assessment of return to pre-COVID-19 health (Figure). For all measures, increasing the consecutive days required for confirmation from 2 to 3 or 4 had a modest impact on median time to the outcome being met, consistent with few participants experiencing relapsing symptoms.
Outcomes based on symptom resolution (A) or improvement (C) are promising for evaluating COVID-19 treatment response, with good internal validity with self-assessment of return to pre-COVID-19 health. A valid symptom outcome measure may be preferred over hospitalization/death as a primary outcome for outpatient COVID-19 treatment trials as most participants achieve the outcome, increasing power to compare treatments, especially among participants who are at low risk for hospitalization/death.
