Diagnostic Tests

Table of Contents

1. Understanding diagnostic tests
   1. What is a 2 x 2 (read two by two) table, and what is it used for?
   2. Implications in clinical practice
   3. Likelihood ratios
   4. Using likelihood ratios
   5. Conclusion
2. Measures of diagnostic tests
3. Diagnosis

Implications in clinical practice

A good example of the implications of not using a diagnostic test with high sensitivity and specificity is shown in this table taken from the MeReC bulletin. You can see that by using a near patient based serological test instead of a breath test for H.pylori, the number of false positive results increases from 11% of patients to 46% of patients. Which may result in a large number of patients being inappropriately treated.