The addition of a usual-care arm to a two-arm clinical trial often results in additional harm to research subjects, substantially increases trial cost and complexity, and delays knowledge acquisition.
We discuss the pros and cons of including usual care as a control arm in clinical trials of nonpharmacologic interventions. Usual care is a term used to describe the full spectrum of patient care practices in which clinicians have the opportunity (which is not necessarily seized) to individualize care. The decision to use usual care as the control arm should be based on the nature of the research question and the uniformity of usual-care practices. The use of a usual-care arm in a two-arm trial should be considered for trials of investigational drugs or devices, for trials that propose to test interventions that lie well outside usual-care practices, or for trials where the research question per se is to compare a strategy against usual care. Examples of the latter include pragmatic effectiveness trials of clinical pathways or protocolized-care versus usual-care practices. Randomized intervention trials can be safely conducted and monitored using two treatments that lie within the range of usual-care practices if both approaches are considered prudent and good care for the target population.
Thompson et al. (2007) conducted a review in Critical illness. Usual care control groups vs. Active control groups was evaluated. The addition of a usual-care arm to a two-arm clinical trial often results in additional harm to research subjects, substantially increases trial cost and complexity, and delays knowledge acquisition.