ABSTRACT
Background: Due to unknown features of the COVID-19 disease and complexity of the patient population, standard clinical trial designs on treatments may not be optimal in such patients. We propose two independent clinical trials designs based on careful grouping of patient and outcome measures. Methods: Using the World Health Organization ordinal scale on patient status, we classify treatable patients (Stages 3-7) into two risk groups. Patients in Stages 3, 4 and 5 are categorized as the intermediate-risk group while patients in Stages 6 and 7 are categorized as the high-risk group. To ensure that an intervention, if deemed efficacious, is promptly made available to vulnerable patients, we propose a group sequential design incorporating four factors stratification, two interim analyses, and a toxicity monitoring rule for the intermediate-risk group. The primary response variable (binary variable) is based on the proportion of patients discharged from hospital by the 15 th day. The goal is to detect a meaningful improvement in this response rate. For the high-risk group, we propose a group sequential design incorporating three factors stratification, two interim analyses, and without toxicity monitoring. The primary response variable for this design is the 30 days mortality, and the goal is to detect a meaning reduction in mortality rate. Results: Required sample size and toxicity boundaries are calculated for each scenario. Sample size requirements for the designs with interim analyses are marginally greater than the ones without. In addition, for both the intermediate-risk group and the high-risk group, conducting two interim analyses have almost identical required sample size compared with just one interim analysis. Conclusions: We recommend using binary outcome with composite endpoints for those in Stages 3, 4 and 5 with a power of 90% to detect an improvement of 20% in response rate, and 30 days mortality rate outcome for those in Stages 6 and 7 with a power of 90% to detect 15% (effect size) reduced mortality rate, in the trial design. For the intermediate-risk group, two interim analyses for efficacy evaluation along with toxicity monitoring are encouraged. For the high-risk group, two interim analyses without toxicity monitoring is advised.