Study Design: Adaptive RCT

Randomized Controlled Trial (RCT)

A randomized controlled trial (RCT) randomly assigns participants into either a treatment arm or control arm. The only expected difference between the two arms is the outcomes being studied. In the ATTACC-CAP trial, eligible patients who consent to the clinical trial will be randomized using the REDCap portal. Patients will randomly (50/50) be allocated therapeutic heparin (treatment arm) or local standard of care (control arm). 

Adaptive Design

The ATTACC-CAP trial design is adaptive, which allows for modifications to the trial once it’s started without compromising the validity of the trial. For this trial, a sequence of periodic analyses will be conducted based on enrollment rate. At each interim analysis, the trial can reach a trial conclusion within any of the defined risk groups which would stop randomization in that risk group in favour of control (standard of care) or therapeutic-dose anticoagulation with heparin.

Risk groups, also known as subgroups, will be divide into three different groups: severity of illness, pathogens (type of virus or bacteria), and/or biomarkers (biological characteristics that tell us something about an organism). At each interim analysis, the trial will look at each subgroup to see if the trial intervention is significantly benefitting or harming one population within a subgroup more than another. For example, the trial may conclude that those with viral influenza A and B benefit more from therapeutic anticoagulation than other pneumonia pathogens. At an interim analysis, it may also be determined that further enrollment into one or more subgroup may be necessary as a decisive decision cannot be made without more data.