How to appraise a clinical trial critically
clinicians wish to base their therapeutic decisions
on scientific data but are often overwhelmed by the
number of case reports, open series and other therapeutic
trials published each year. It is essential to develop
a personal screening plan that can alert the clinician
to which reports deserve extra attention, as they may
alter management, and to which reports can be ignored.
The first step is to review the abstract. Decisions
related to therapeutics should be based on 'randomized',
'controlled', 'double-blinded', 'clinical trials'. If
these key words are not included in the abstract, it
is unlikely that the report will change clinical practice.
Each of these terms describes an essential element that
attempts to assure that the results of the trial will
be unbiased and generally applicable to clinical practice.
The next step is to examine the 'Methods' section. Clinicians
should be interested in the inclusion and exclusion
criteria. Two questions arise. First, do the study participants
resemble patients in your practice? Second, how many
patients were assessed in order to enrol the study population?
If only a few of the patients screened actually entered
the trial the results may not be of use for the general
population with the disease. Another important screening
process is to review the 'Statistical' section. It is
not necessary to be a statistician, but one should read
the section to determine whether a sample size calculation
was performed and whether confidence intervals have
been calculated around the major end-points. By remembering
these key concepts, clinicians can reduce the number
of journal articles they read without compromising their
ability to be informed of major breakthroughs in the
management of disease.