1. Improving Decisions in Clinical Medicine Chapter 8

2. Bayes Theorum  A somewhat convoluted theory that is used in the mathematical exercise of determining probability.  If a patient has symptom A what is the probability that the symptom is caused by a certain disease?

3. Example… A fourteen year old girl goes to the county fair, during the course of a three hour visit to the fair, she eats a funnel cake, cotton candy, and a candy apple after consuming a foot-long chili dog.

4.  Two hours after arriving home from the fair she is rushed to the local ER for stomach pains, dizziness and vomiting.

5. The Visit  Upon arrival at the ER, blood chemistries and a CBC are drawn as well as collection of a free catch urine sample.

6. Patient Data  Examination:  Temperature 98.7  Pulse 84  Respiration 24  Weight 136  Height 5 ft 6  Laboratory Report  Complete Blood Count: within normal limits  Chemistries: Within normal limits except for glucose (sugar) which is 198  Normal glucose reading is 100-120

7. Symptoms of Diabetes  Increased water consumption  Weight gain or loss (unexpected)  Glucose readings that are above normal  Increased and frequent urination  Frequent night-time urination

8. Question  Based on the history of the patient and what we now know of diabetes, does this patient have diabetes?

9. Bayes Theorum  A way of predicting through observation of probability whether or not a symptom is caused by a disease.

10. Hmmm…  If a population has a low prevalence (occurrence) of a disease, it is likely that positive results may be false positives  They should be examined further before a diagnosis is positively made  This is an area where good epidemiological examination can make all the difference in avoiding a panic.

11. Evidence Based Medicine  A form of medical practice that:  Bases a diagnosis on symptoms + prevalence  Relies heavily on the use of Bayes Theorum  Must perform tests to rule out diseases as part of the diagnostic process  Uses a sequential approach to tests  Begin with most sensitive test for fastest and most accurate results  Continues with other tests in a sequence until a satisfactory answer is arrived at (i.e. diagnosis)

12. Decision Trees  A method of improving decision making in times of uncertainly  A way of outlining ones thoughts and rationale concerning a medical dilemma  Create a decision tree  Identify/set limits to the problem  Diagram options  Obtain information on each option  Compare the values  Perform sensitivity analysis to arrive at an answer

13. When to Use Decision Trees  Clinical settings  Public health problem solving

14. Meta-analysis  Defined:  Collection of related methods used to combine data from similar studies to obtain the best estimate.  Types:  Pooled Quantitative Analysis: deals with actual numbers (i.e. quantity)

15. Continued  Methodological Qualitative Analysis: deals with quality or benefits derived from something such as a treatment or drug therapy.

16. Questions

17. Discussion Time

18. Page 130, Figure 8-2  If you took your mother to the ER with the symptom of chest pain at rest, how would you feel about a physician using Figure 8-2 as a basis for his treatment decisions?

19. The End Any questions, concerns or discourse on assignments so far within the course?