Comparing diagnostic tests: a simple graphic using likelihood ratios

Stat Med. 2000 Mar 15;19(5):649-63. doi: 10.1002/(sici)1097-0258(20000315)19:5<649::aid-sim371>;2-h.


The diagnostic abilities of two or more diagnostic tests are traditionally compared by their respective sensitivities and specificities, either separately or using a summary of them such as Youden's index. Several authors have argued that the likelihood ratios provide a more appropriate, if in practice a less intuitive, comparison. We present a simple graphic which incorporates all these measures and admits easily interpreted comparison of two or more diagnostic tests. We show, using likelihood ratios and this graphic, that a test can be superior to a competitor in terms of predictive values while having either sensitivity or specificity smaller. A decision theoretic basis for the interpretation of the graph is given by relating it to the tent graph of Hilden and Glasziou (Statistics in Medicine, 1996). Finally, a brief example comparing two serodiagnostic tests for Lyme disease is presented. Published in 2000 by John Wiley & Sons, Ltd.

Publication types

  • Comparative Study

MeSH terms

  • Diagnostic Tests, Routine*
  • False Positive Reactions
  • Humans
  • Likelihood Functions
  • Lyme Disease / diagnosis
  • Models, Statistical*
  • ROC Curve
  • Sensitivity and Specificity
  • Serologic Tests