Randomized controlled trial A randomized controlled trial (RCT)
(or randomized comparative trial) is a specific type of
scientific experiment, and the gold standard for a clinical
trial. RCT are often used to test the efficacy and/or
effectiveness of various types of medical intervention within a
patient population. RCT may also provide an opportunity to
gather useful information about adverse effects, such as drug
reactions. The key distinguishing feature of the usual RCT is
that study subjects, after assessment of eligibility and
recruitment, but before the intervention to be studied begins,
are randomly allocated to receive one or other of the
alternative treatments under study. Random allocation in real
trials is complex, but conceptually, the process is like tossing
a coin. After randomization, the two (or more) groups of
subjects are followed in exactly the same way, and the only
differences between the care they receive, for example, in terms
of procedures, tests, outpatient visits, follow-up calls etc