By using records of the US Department of Veterans Affairs, Müller and Sonnenberg1 were able to
undertake a very large case-control study of the
efficacy of endoscopic screening for colorectal cancer.
However, the disadvantage of using data from this source
is the inability to characterize individual endoscopic examinations regarding their intent, ie, screening vs response to a symptom or sign. The inclusion of nonscreening examinations in the analysis would serve to minimize
the estimated efficacy of screening, since patients with
fatal colorectal cancer would be far more likely to have
had an examination of this type than controls without
colorectal cancer. Recognizing this potential bias, Müller
and Sonnenberg restricted their comparison to examinations performed before those that led to the diagnosis
of colorectal cancer. However, this approach has its own
drawbacks, for it will effectively ignore the most relevant portion of the screening history of those fatal cases
Weiss NS. Definition of Screening Status in Case-Control Studies of the Efficacy of Endoscopy. Arch Intern Med. 1996;156(10):1113. doi:10.1001/archinte.1996.00040041113013
Customize your JAMA Network experience by selecting one or more topics from the list below.
Create a personal account or sign in to: