Screening tests IV

doi:10.1136/bmj.b4365

Published 28 October 2009, doi:10.1136/bmj.b4365
Cite this as: BMJ 2009;339:b4365

Endgames

Statistical question

Screening tests IV

Philip Sedgwick, senior lecturer in medical statistics

¹ Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London SW17 0RE

p.sedgwick@sgul.ac.uk

The first 150 words of the full text of this article appear below.

A study investigated the performance of the CAGE questionnaireas a screening tool for alcohol abuse or alcohol dependencyin primary care. The CAGE questionnaire consists of four questionsabout alcohol behaviour, each with a "yes" or "no" response.Clinical interview was used as the diagnostic test ("gold standard")for alcohol abuse or alcohol dependency. A total of 1970 individualswere investigated and the results obtained are shown in table1. ¹

View this table:

Table 1 Cross tabulation of the number of "yes" responses on CAGE questionnaire against clinical diagnosis

A minimum number of "yes" responses is required for the screeningtest to identify an individual as screen "positive" and subsequentlyrecommend clinical interview. If the threshold for "positive"on the screening test was increased from one or more ( $≥$ 1) totwo or more ( $≥$ 2) "yes" responses, which of the following, ifany, would be observed?

a) The sensitivity would decrease

b) The . . . [Full text of this article]