Epidemiologist prefer to play around with measurable phenomena. This
can make them blind for far more important sources of unreliability,
i.e. the reliability of entire diagnostic procedures. This mirrors
the difference between efficacy under ideal circumstances in
therapeutic procedures versus effectiviness in daily practice.
The discussion on inter-intrarater reliability of radiologists'
judgements of x-rays is all on re-assessing the same picture.
However, the problem in radiology is the reliability of the
assessment of the patient. This requires two similar x-rays of the
same patient, which could be considered as unethical (though to my
opinion unreliable x-rays, even when disregarding unreliable
judgements, is far more unethical). I am quite confident that
x-paranasal sinus, not to speak of x-digestive tract pictures with
contrast infusion, has a very low test-retest reliability.
Any radiologist around how dares to challenge this part of the
validity of his profession?
Nico van Duijn, MD PhD MSc
Depart General Practice
Academic Medical Centre
University of Amsterdam
Amsterdam
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