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Diagnostics in EM; test thresholds and likelihood ratios

Diagnostics in EM; test thresholds and likelihood ratios. Published courtesy of the CEM FOAMed Network http:// www.cemfoamed.co.uk /portfolio/diagnostics-in- em /. Everything we do in a patient assessment is a test Including questions we ask. Test thresholds.

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Diagnostics in EM; test thresholds and likelihood ratios

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  1. Diagnostics in EM; test thresholds and likelihood ratios Published courtesy of the CEM FOAMed Network http://www.cemfoamed.co.uk/portfolio/diagnostics-in-em/

  2. Everything we do in a patient assessment is a testIncluding questions we ask

  3. Test thresholds

  4. Within the test thresholds; appropriate testing

  5. Below a test threshold;more likely to harm than help a patient by testing

  6. Above a test threshold; more likely to harm than help a patient by testing

  7. Within a test threshold;appropriate testing

  8. How do we use all of this information?? 100 % Likelihood of diagnosis being correct Diagnosis considered Below test threshold 0%

  9. How do we use all of this information?? 100 % Above test threshold Likelihood of diagnosis being correct Diagnosis considered 0%

  10. How do we use all of this information?? 100 % Above test threshold Appropriate testing Likelihood of diagnosis being correct Diagnosis considered Below test threshold 0%

  11. Likelihood ratios

  12. Positive Likelihood ratio;a high number is powerful>>1

  13. Negative Likelihood ratio;a small number is powerful<< 1

  14. Fagan’s nomogram

  15. Application of serial tests 100 % Finding 3 Above test threshold Finding 2 Likelihood of diagnosis being correct Finding 1 Diagnosis considered Below test threshold 0%

  16. Correct testingCorrect testCorrect circumstanceCorrect patient

  17. Perry et al. Sensitivity of coputed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ 2011; 343:d4277 doi. 10.1136/bmj.d4277

  18. Han et al., The Role of Cardiac Risk Factor Burden in Diagnosing Acute Coronary Syndromes in the Emergency Department Setting. Ann Emerg Med. 2007; 49

  19. Who not to test 100 % Likelihood of diagnosis being correct Diagnosis considered Below test threshold 0%

  20. Who not to test but to treat 100 % Above test threshold Likelihood of diagnosis being correct Diagnosis considered 0%

  21. Who should be tested 100 % Appropriate testing Likelihood of diagnosis being correct Diagnosis considered 0%

  22. Correct testingCorrect testCorrect circumstanceCorrect patient

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