Clinical Research - An Introduction
INTRODUCTION
We define a clinical trial as a prospective study comparing the effect and value of intervention(s)
against a control in human beings. Note that a clinical trial is prospective, rather than retrospective. Study participants must be followed
forward in time. Each participant however, must be
followed from a well-defined point in time, which becomes time zero or
baseline for the study. A clinical trial must employ one or more intervention techniques. These may be single or
combinations of diagnostic, preventive, or therapeutic drugs, biologics,
devices, regimens, or procedures. Intervention techniques should be applied to
participants in a standard fashion in an effort to change some aspect.
Follow-up of people over a period of time without active intervention may
measure the natural history of a disease process, but it does not constitute a
clinical trial. Without active intervention the study is observational because
no experiment is being performed. Early phase studies may be controlled or
uncontrolled. Although common terminology refers to phase I and phase II
trials, because they are sometimes uncontrolled. A trial contains a control group against which the intervention group is compared. At
baseline, the control group must be sufficiently similar in relevant respects
to the intervention group in order that differences in outcome may reasonably
be attributed to the action of the intervention. Most often a new intervention
is compared with, or used along with, best current standard therapy. Each clinical trial must incorporate participant safety
considerations into its basic design. Equally important is the need for, and
responsibility of, the investigator to fully inform potential participants about
the trial, including information about potential benefits, harms, and treatment
alternatives. Unlike animal studies, in clinical trials the investigator cannot
dictate what an individual should do. He can only strongly encourage
participants to avoid certain medications or procedures which might interfere
with the trial. Since it may be impossible to have “pure” intervention and
control groups, an investigator may not be able to compare interventions, but
only intervention strategies. Strategies refer to attempts at getting all
participants to adhere, to the best of their ability, to their originally
assigned intervention. When planning a trial, the investigator should recognize
the difficulties inherent in studies with human subjects and attempt to estimate
the magnitude of participants’ failure to adhere strictly to the protocol. The ideal clinical trial is one that is
randomized and double-blind. Deviation from this standard has potential drawbacks. In some
clinical trials, compromise is unavoidable, but often deficiencies can be
prevented by adhering to fundamental features of design, conduct, and analysis.
