Skip to main content

Simplifying likelihood ratios

Abstract

Likelihood ratios are one of the best measures of diagnostic accuracy, although they are seldom used, because interpreting them requires a calculator to convert back and forth between “probability” and “odds” of disease. This article describes a simpler method of interpreting likelihood ratios, one that avoids calculators, nomograms, and conversions to “odds” of disease. Several examples illustrate how the clinician can use this method to refine diagnostic decisions at the bedside.

This is a preview of subscription content, access via your institution.

References

  1. Fagan TJ. Nomogram for Bayes’ theorem. N Engl J Med. 1975;293:257.

    PubMed  CAS  Google Scholar 

  2. http://cebm.jr2.ox.ac.uk/docs/nomogram.html. Accessed February 15, 2002.

  3. Williams JW, Simel DL. Does this patient have ascites? How to divine fluid in the abdomen. JAMA. 1992;267:2645–8.

    PubMed  Article  Google Scholar 

  4. Simel DL, Halvorsen RA, Feussner JR. Quantitating bedside diagnosis: clinical evaluation of ascites. J Gen Intern Med. 1988;3:423–8.

    PubMed  Article  CAS  Google Scholar 

  5. Badgett RG, Tanaka DJ, Hunt DK, et al. Can moderate chronic obstructive pulmonary disease be diagnosed by historical and physical findings alone? Am J Med. 1993;94:188–96.

    PubMed  Article  CAS  Google Scholar 

  6. Lee TH, Cook EF, Weiserg M, Sargent RK, Wilson C, Goldman L. Acute chest pain in the emergency room: identification and examination of low-risk patients. Arch Intern Med. 1985;145:65–9.

    PubMed  Article  CAS  Google Scholar 

  7. Aronow WS, Kronzon I. Prevalence and severity of valvular aortic stenosis determined by Doppler echocardiography and its association with echocardiographic and electrocardiographic left ventricular hypertrophy and physical signs of aortic stenosis in elderly patients. Am J Cardiol. 1991;67:776–7.

    PubMed  Article  CAS  Google Scholar 

  8. Buchsbaum DG, Buchanan RG, Centor RM, Schnoll SH, Lawton MJ. Screening for alcohol abuse using CAGE scores and likelihood ratios. Ann Intern Med. 1991;115:774–7.

    PubMed  CAS  Google Scholar 

  9. Palafox M, Guiscafre H, Reyes H, Munoz O, Martinez H. Diagnostic value of tachypnoea in pneumonia defined radiologically. Arch Dis Child. 2000;82:41–5.

    PubMed  Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Steven McGee MD.

Additional information

Received from the University of Washington Seattle-Puget Sound VA Health Care System, Seattle, Wash.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

McGee, S. Simplifying likelihood ratios. J GEN INTERN MED 17, 647–650 (2002). https://doi.org/10.1046/j.1525-1497.2002.10750.x

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1046/j.1525-1497.2002.10750.x

Key words

  • likelihood ratio
  • diagnostic accuracy