Abstract
This article is concerned with the sensitivity, specificity, predictive values, and other metrics associated with screening tests. It has direct origins in two previous articles. In this third article, the author of the first article writes about topics and issues that were addressed only minimally in his previous article and expands on topics raised by authors of the second article. In particular, attention is turned to wording and terminology that can be idiosyncratic and confusing with regard to screening versus diagnosis as well as to issues associated with reference (“gold”) standards and screening tests, and to the importance of cutpoints and prevalence in relation to metrics associated with screening tests. The primary aims are to help readers attain clarity about topics that they might have felt unsure about; gain reassurance about conceptual difficulties in the field that, once recognized for what they are, can become less problematic because it is possible to be confident about not being confident; and, where appropriate, adopt an appropriately skeptical attitude about screening tests and their associated metrics. Examples are drawn from the use of ankle–brachial and toe–brachial indices for identifying peripheral artery disease, although wider applicability is intended.
Highlights
In November 2017, Frontiers in Public Health - Epidemiology published an article that I authored concerning sensitivity, specificity, and predictive values (Trevethan, 2017b)
There are additional issues, and more extensive issues within those considered below, but the issues raised serve to indicate that the validity of neither reference standards nor screening tests should be assumed unquestioningly and that, where possible, steps should be taken to improve the sensitivity, specificity, predictive values, and other metrics associated with screening tests by addressing problems related to both reference standards and screening tests
Predominant among these is that the foundations of screening tests, and the metrics associated with those tests, are by no means simple and that some degree of cautious sophistication needs to be exercised when evaluating and using them
Summary
In November 2017, Frontiers in Public Health - Epidemiology published an article that I authored concerning sensitivity, specificity, and predictive values (Trevethan, 2017b). I dealt with ways in which those metrics could inform decision making in health contexts The impetus for this was my sense that researchers and clinicians seem to have difficulty understanding those metrics—a lack of understanding that has been borne out empirically (Manrai et al, 2014; Puhan et al, 2005; Steurer et al, 2002; Whiting, Davenport, et al, 2015). In order to support these topics, I use examples relating to the ankle–brachial index (ABI) and toe–brachial index (TBI), both of which are noninvasive indicators of peripheral artery disease (PAD) They are commonly regarded as screening rather than diagnostic tests and are ideal for current purposes because they have features that permit mhs.ideasspread.org. ABIs and TBIs inevitably have some features that do not translate readily to other contexts, they are used because, without concrete examples, information and issues can fail to become apparent or to consolidate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
