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# Vita

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I would consider myself lucky .. if I understood this as well as the presenter Mr Iyengar ..

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### Vita

1. 1. VITA-An Interactive 3-D Visualization System to Enhance Student Understanding of Mathematical Concepts in Medical Decision-making<br />M Sriram Iyengar, PhD<br />Asst. Professor, School of Health Information Sciences, University of Texas Health Science Center at Houston<br />Informatics Research Scientist, Medical Informatics and Health Care Systems, NASA Johnson Space Center, Houston, TX<br />John R Svirbely, MD<br /> TriHealth, Cincinnati, Ohio<br />Mirabela Rusu, MS<br />Graduate Student,School of Health Information Sciences, University of Texas Health Science Center at Houston<br />Jack W Smith, MD, PhD<br /> Professor and Dean, School of Health Information Sciences, University of Texas Health Science Center at Houston<br />
2. 2. Mathematics of Diagnostic Testing <br />A diagnostic test may be a biochemical assay (BNP, PSA, other) or other analysis.<br />If the assay result is greater (or lesser) than a cutoff value then the presence (or absence) of disease is concluded.<br />To analyze the test performance we use:<br />Sensitivity = P(Test positive | Disease present )<br />Specificity = P(Test negative | Disease not present ) <br />False Positive rate = 1 - specificity<br />ROC curve: Plot of Sensitivity vs. False Positive rate<br />Area under ROC: the closer to 1 the better<br />
3. 3. Mathematics of Diagnostic Testing 2<br />However, the Post-test Predictive Values are more useful for diagnostic purposes.<br />Positive Predictive Value = P(Disease exists| Test positive)<br />Negative Predictive Value = P(Disease not present | Test negative)<br />Both incorporate disease prevalence and are computed using Bayes formula.<br />
4. 4. Post-Test Predictive Values are complex<br /> Four Dimensional relationship!<br />
5. 5. VITA <br />Interactive software for 3-D visualization<br />3-D and 4-D views<br />Provides rotation, zooming and similar functions for graph manipulation<br />Can use a table of cut-off values and generate direct relationships between PPV, NPV and cutoff values for various prevalences.<br />
6. 6. Main Vita Screen<br />
7. 7. 4-D Plot<br />
8. 8. Pred. Values vs Test cutoffs (BNP)<br />
9. 9. VITA Benefits<br />Teaching:<br />Important and complex mathematical concepts in medical decision-making<br />Understand non-linearity in predictive values<br />Understand how a test will perform in a different population<br />Research:<br />Determine optimal cutoff-vales for diagnostic tests<br />Compare performance of diagnostic tests on the basis of predictive vales that are more meaningful to diagnosticians<br />
10. 10. Thank You!!<br />