The randomized clinical trial (RCT) is a powerful tools for clinical researchers, which evaluates the effectiveness of new (or established) treatments while accounting for the effects of unmeasured confounders and selection bias by indication. However, RCTs could answer only a small fraction of important clinical questions as it is usually expensive to perform RCTs, therefor follow-ups are usually short. As RCTs are carried out under an artificial setting and it may be difficult to generalized these conclusions on real-world patients. An alternative solution is to look into observational registries, relative to RCT, they are cheaper and usually having longer follow-ups, however to comparing outcomes between different treatments is sometimes questionable owing to the absence of randomization.
A new paradigm, the Randomized Registry Trial (RRCT), has emerged, which complements the strengths and addresses the weaknesses of a traditional RCT and observational study. The RRCT integrate a RCT into an already-existing high-quality observational registry. Clinical information was already collected for the registry and for other pre-existing databases, the investigators are able to quickly identify potential participants, to enroll thousands of patients in little time, to avoid filling out long case-report forms, to obtain accurate follow-up with minimal effort, and to report their findings, at a significantly lower costs. The RRCT is a rigorous randomized experiment that isolates a causal link (or the absence of one) between a treatment and an outcome, but at the same time, owning to its inexpensiveness, investigators can enroll large numbers of patients, thus offering clinicians insights that are potentially based on a representative sample, a real world population created from consecutively enrolled registry patients.
More details can be found at:
Lauer MS, D’Agostino RBS. The Randomized Registry Trial — The Next Disruptive Technology in Clinical Research? New England Journal of Medicine. 2013 Oct 24;369(17):1579–81.