This is not as obvious as it seems. When I was in school, David
Sackett was the guru of breaking down and arguing about journal
articles. His writings were the basis of all the classes that
I was exposed to in this area. The method I use was greatly shaped
by his teachings.
Obvious or not, the first step is to see if the purported conclusion
of the article applies to your practice or question—if not,
move on.
Next, I look at the methods to see if this was blinded or not,
and how many patients were included. Non-blinded and single-blinded
studies are weaker than double-blind studies (we will get to this),
and small numbers of patients in a study may have conclusions
based that are incorrect based on inclusion bias (more on this
later as well).
In studies with control groups, I check to see if the study and
placebo group were similar in demographics, and exactly what kind
of placebo were they using. Was the placebo truly a sugar pill,
or were they comparing to an expected standard of care.
Finally, what is the gold standard for outcomes. You have a hard
time convincing me of an effect if the measurement tool is the
item you are studying. For example, to measure cardiac catheterization
against a plain stress test for demonstrating coronary lesions
as showing a higher standard of care, well what are we looking
for. Of course the catheterization will show more lesions, but
how many of these are clinically significant and how do we know
that the catheterization is correct if there is no test to check
its validity. It might be better to use the catheterization for
a gold standard if comparing Magnetic Resonance Angiography to
Computed Topography for diagnosis of coronary lesions.
If I believe their conclusion after my scrutiny of their methods,
then I make sure I apply this to only the inclusion group they
used for the study. If the used the population at large—Great!
If they used ambidextrous males between 5 foot 1 inch and 5 foot
3 inches tall with dark hair who had more auto accidents on odd-numbered
Tuesdays as the inclusion group for increased splenic lacerations,
it would be hard to maintain such vigilance to select for this
group in clinical practice.
