08.11.08: the information cycle
DESCRIPTION
Slideshow is from the University of Michigan Medical School's M1 Patients and Populations: Medical Decision-Making Sequence View additional course materials on Open.Michigan: openmi.ch/med-M1PatientsPopulationsTRANSCRIPT
![Page 1: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/1.jpg)
Author(s): Rajesh Mangrulkar, MD, 2009 License: Unless otherwise noted, this material is made available under the terms of the Creative Commons Attribution–Non-commercial–Share Alike 3.0 License: http://creativecommons.org/licenses/by-nc-sa/3.0/
We have reviewed this material in accordance with U.S. Copyright Law and have tried to maximize your ability to use, share, and adapt it. The citation key on the following slide provides information about how you may share and adapt this material. Copyright holders of content included in this material should contact [email protected] with any questions, corrections, or clarification regarding the use of content. For more information about how to cite these materials visit http://open.umich.edu/education/about/terms-of-use. Any medical information in this material is intended to inform and educate and is not a tool for self-diagnosis or a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional. Please speak to your physician if you have questions about your medical condition. Viewer discretion is advised: Some medical content is graphic and may not be suitable for all viewers.
![Page 2: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/2.jpg)
Citation Key for more information see: http://open.umich.edu/wiki/CitationPolicy
Use + Share + Adapt
Make Your Own Assessment
Creative Commons – Attribution License
Creative Commons – Attribution Share Alike License
Creative Commons – Attribution Noncommercial License
Creative Commons – Attribution Noncommercial Share Alike License
GNU – Free Documentation License
Creative Commons – Zero Waiver
Public Domain – Ineligible: Works that are ineligible for copyright protection in the U.S. (USC 17 § 102(b)) *laws in your jurisdiction may differ
Public Domain – Expired: Works that are no longer protected due to an expired copyright term.
Public Domain – Government: Works that are produced by the U.S. Government. (USC 17 § 105)
Public Domain – Self Dedicated: Works that a copyright holder has dedicated to the public domain.
Fair Use: Use of works that is determined to be Fair consistent with the U.S. Copyright Act. (USC 17 § 107) *laws in your jurisdiction may differ Our determination DOES NOT mean that all uses of this 3rd-party content are Fair Uses and we DO NOT guarantee that your use of the content is Fair. To use this content you should do your own independent analysis to determine whether or not your use will be Fair.
{ Content the copyright holder, author, or law permits you to use, share and adapt. }
{ Content Open.Michigan believes can be used, shared, and adapted because it is ineligible for copyright. }
{ Content Open.Michigan has used under a Fair Use determination. }
![Page 3: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/3.jpg)
Patients and Populations Medical Decision-Making: The Information
Cycle
Rajesh S. Mangrulkar, M.D.
Fall 2008
![Page 4: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/4.jpg)
A Clinical Tale
• 20 year-old woman presents for genetic testing
• Mother had breast and ovarian cancer, likely has the BRCA gene (autosomal dominant)
• With this assumption, the patient’s likelihood of having the gene is…
• She decides not to get tested. 50%
![Page 5: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/5.jpg)
The Tale Continues…FFwd
• At age 75 she has not been diagnosed with breast or ovarian cancer.
• Is her probability of having the BRCA gene different at age 75 than it was at age 20? – Yes: it is lower – How much lower?
![Page 6: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/6.jpg)
Diagnostic Reasoning: Probabilistic Reasoning
Probability: The likelihood of the occurrence of an event.
• P (X) = the probability of event X • P(BRCA) = the probability that a patient
carries the BRCA gene
![Page 7: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/7.jpg)
Prior Probabilities
• Based on many factors: – Clinician experience – Patient demographics – Characteristics of the patient presentations
(history and physical exam) – Previous testing – Genetic knowledge (in this case)
• P(BRCA) = 50%
![Page 8: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/8.jpg)
Conditional Probabilities
• What is the probability of event B, given an event A? Written as P(B | A). – Example: P (BRCA | no breast cancer)
• Key concept: – Conditional probabilities can be combined
with prior probabilities to create joint probabilities
![Page 9: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/9.jpg)
Basic Probabilistic Rules Examples of types of Events
• Dependent events: occurrence of 1 depends to some extent on the other – Example: The same person passing step 1 of the
boards and then passing step 2 of the boards 2 years later.
• Independent events: both can occur – Example: 2 different people passing step 1 of the
boards • Mutually exclusive events: cannot both occur
– Example: A person getting >250 on step 1 of the boards, or the same person getting 220-250 on step 1.
![Page 10: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/10.jpg)
Combining Probabilities of Events
• Pr (A B) = Pr (A) + Pr (B) – If A and B are mutually exclusive events
• Pr (A B) = Pr (A) * Pr (B) – If A and B are independent events
• Pr (A B) = Pr (A) * Pr (B|A) – If A and B are dependent events (Joint
probability)
= OR = AND
![Page 11: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/11.jpg)
Back to our story
75 yo woman whose mother very likely had the BRCA gene, but who has not herself been diagnosed with breast cancer.
• Our patient wants to know: – What is P (BRCA | no breast ca)?
![Page 12: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/12.jpg)
Considering both sides…
• Step 1: P (BRCA and no breast cancer) = P(BRCA) * P(no breast ca | BRCA) = 0.5 * 0.3 (from studies) = 0.15
• Step 2: P (NO BRCA and no breast ca) = P(NO BRCA)*P(no breast ca|NO BRCA) = 0.5 * 0.875(from studies) = 0.4375
![Page 13: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/13.jpg)
But that doesn’t tell the full story…
• Joint probabilities – P (BRCA and no breast ca) = 0.15 – P (NO BRCA and no breast ca) = 0.4375
• The assumption is that these are NOT independent events.
• Again, our patient wants to know: – What is P (BRCA | no breast ca)?
![Page 14: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/14.jpg)
WARNING
CONFUSING MATH
AHEAD
![Page 15: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/15.jpg)
Step 3: Bayes Theorem
• Conditional probability is the relative proportion of the relevant joint probability to the sum of all the joint probabilities.
• P(BRCA | no breast ca) = P(BRCA) * P (no breast ca | BRCA) P (no breast ca)
• P (no breast ca) = sum of all the joint probabilities
• P (no breast ca & BRCA) • P (no breast ca & NOT BRCA)
![Page 16: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/16.jpg)
Applying Bayes Theorem
• P (BRCA | no breast ca) = 0.15 ------------------- = 26% 0.15 + 0.4375
• 26% is significantly lower than 50% (our
prior probability)
![Page 17: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/17.jpg)
Why is this important?
• Illustration of changing probabilities, and shifting uncertainty… …because of test results …because of events …because of time
• Fundamentally, clinicians deal with probabilities and uncertainty with each patient they encounter
![Page 18: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/18.jpg)
Final tale: Diagnostic Reasoning
• The case: A 56 year old man without heart disease presents with sudden onset of shortness of breath.
• Description of the problem: Yesterday, after flying in from California the day before, the patient awoke at 3AM with sudden shortness of breath. His breathing is not worsened while lying down.
![Page 19: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/19.jpg)
Diagnostic Reasoning: Your Intake
• Q: “What other symptoms were you feeling at the time?”
• A: He has had no chest pain, no leg pain, no swelling. He just returned yesterday from a long plane ride. He has no history of this problem before. He takes an aspirin every day. He smokes a pack of cigarettes a day.
![Page 20: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/20.jpg)
Diagnostic Reasoning: Baby Steps
Prior to Lectures on 8/18… • What are you thinking may be going on
at this time? In other words, generate a differential diagnosis of possibilities…
• Assign likelihoods to each possibility • Place the possibilities in descending
order of likelihood
![Page 21: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/21.jpg)
Ask
Acquire
Appraise
Apply
Ask
Acquire
Thread 1: Information Retrieval
R. Mangrulkar
![Page 22: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/22.jpg)
Riddle me this...
• How many questions do clinicians ask while they care for patients?
• How can knowledge of question structure improve the efficiency of the information retrieved?
4 per patient
(1) Targeting Information Resources (2) Generating Search Terms
![Page 23: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/23.jpg)
Early Hypothesis (Basic Science theory, case reports, cross-sectional studies)
Mature Hypothesis (Consistent support from observational studies)
Confirm Causal Link (Large prospective randomized trials)
Optimal Decision Making (Use information on treatment benefit, risks and costs from trials and
observational studies, simulation models)
Research: Questions New Knowledge
R. Mangrulkar
![Page 24: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/24.jpg)
Objectives of today’s session
• By the end of this lecture, you should be able to… – demonstrate an understanding of the difference
between background and foreground clinical questions
– appreciate how individual targeted searches for the answers to clinical questions drive self-directed learning that is crucial for all practitioners
– be able to craft foreground questions for both diagnosis and treatment, using the PICO format
![Page 25: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/25.jpg)
• Step 1: Question Search for Answer • Step 2: Assess the strength of answer • Step 3: Weigh against:
– Patient Values – Physician Values – Society’s Values
Patient Care: Questions Decisions
![Page 26: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/26.jpg)
A Tale: The Concierge
• The case: You and your friend are at the Drake Hotel in Chicago, and need to find a place to eat for dinner.
• Description: You both are vegetarian. You are both in the mood for Asian cuisine. You only have 2 hours to eat, so you don’t want to take a cab, car or train. You both are on a tight budget so entrees should not be expensive.
![Page 27: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/27.jpg)
The Concierge: Scenario #1
• Q: Could you suggest a place for my “friend” and I to eat close by?
• A: What kind of restaurant? • Q: Well, it should be around here. • A: We have dozens of excellent
restaurants close to the Drake. • Q: Yeah, one of those… • A: Can you be more specific? • Q: Well, we’re kind of in a hurry so
it should be close by...
![Page 28: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/28.jpg)
The Concierge: Scenario #2
• Q: Can you help us find a restaurant? • A: Sure. What are you looking for? • Q: Well, we’re in the mood for Thai
cuisine with an excellent vegetarian selection. It should be walking distance from here, with a nice view of the city. Not too pricey, say $15 per entrée.
• A: Ah! I have the perfect place…Thai Peppers. Let me call ahead and let them know you’ll be coming.
![Page 29: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/29.jpg)
What makes a good question?
• #1: Could you suggest a place for my “friend” and I to eat close by?
• #2: Can you help us find a vegetarian Thai restaurant, walking distance from here, about $15 per entrée?
What aspects of the second question predicted its success at retrieving a place that the
customers were satisfied with?
![Page 30: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/30.jpg)
• Purposes – Target resources – Define search terms – Define what you and the patient care about
• Two Types – Background – Foreground
The Well-Structured Clinical Question
![Page 31: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/31.jpg)
Anatomy of a Background Question
• What • How • Where • When • Who • Why
![Page 32: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/32.jpg)
The Riddler
How much dirt is in a hole 3 acres square and 200 feet deep?
What has neither flesh, bone, nor nail yet has 4 fingers and a thumb?
When is the top of a mountain like a saving's account?
Why is a bear like a fallen tree?
Which president wears the largest hat?
54/67 (81%) of all questions posed by the Riddler were Background-type
None, because it's a hole A glove When it peaks one's interest A bear lumbers and a fallen tree becomes lumber The one with the biggest head
![Page 33: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/33.jpg)
Anatomy of a Background Question
• What • How • Where • When • Who • Why
• Disorder • Syndrome • Finding • Health state • Concern
![Page 34: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/34.jpg)
Background Questions -- Examples
• Who should get influenza vaccine and when?
• Which drugs to treat HIV can cause pancreatitis?
• What is the metabolic pathway for cholesterol synthesis?
• Why do patients with sleep apnea have high blood pressure?
![Page 35: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/35.jpg)
• Background: Designed to improve general knowledge about a subject
• Foreground: Patient-specific questions, strong implications for decisions, often with comparisons
Background vs. Foreground Questions
![Page 36: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/36.jpg)
An Evolution in Question Type
0102030405060708090100
M1-M2 M3-M4 Residency Practice
ForegroundBackground
R. Mangrulkar
![Page 37: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/37.jpg)
• Background: Designed to improve general knowledge about a subject
• Foreground: Patient-specific questions, strong implications for decisions, often with comparisons
Background vs. Foreground Questions
![Page 38: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/38.jpg)
Background Questions: A Case
Using the following case, jot down 3 questions with your partner that may help you care for this patient:
A 42 year old woman comes to her primary care practitioner’s office for follow up of her diabetes. She is currently on glyburide 10 mg twice daily. However, her morning and evening blood sugars still stay elevated. You are the medical student who sees this patient with your attending. Afterwards, your attending asks whether you think she should add metformin to her regimen. You say that you don’t know because your knowledge of diabetes medications are sketchy.
![Page 39: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/39.jpg)
Background Questions
• What kind of medication is glyburide? • In what classes of medication do metformin
and glyburide fall? • What is the initial dosage of metformin? • What are the adverse effects of metformin
that I must be cautious about? • Is it safe to be on glyburide and metformin at
the same time?
![Page 40: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/40.jpg)
Sources for Background Questions
• Course notes, lectures, syllabi • Textbooks
– MD Consult – Stat!Ref – Up-To-Date
• Review articles • Practice Guidelines
![Page 41: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/41.jpg)
• Background: Designed to improve general knowledge about a subject
• Foreground: Patient-specific questions, strong implications for decisions, often with comparisons
Background vs. Foreground Questions
![Page 42: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/42.jpg)
Foreground Questions -- Examples
• In patients with chronic atrial fibrillation over the age of 70, does warfarin anticoagulation reduce the rate of stroke and death when compared with aspirin?
• In patients with acute chest pain of less than 6 hours’ duration, what is the diagnostic accuracy of a single troponin level when compared with serial EKG’s and enzymes?
Therapy Diagnosis
![Page 43: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/43.jpg)
Foreground Questions -- Examples
Therapy • In patients with chronic atrial fibrillation over
the age of 70, does warfarin anticoagulation reduce the rate of stroke and death when compared with aspirin?
Diagnosis • In patients with acute chest pain of less than
6 hours’ duration, what is the diagnostic accuracy of a single troponin level when compared with serial EKG’s and enzymes?
![Page 44: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/44.jpg)
PICO: A Tool to Structure the Foreground Question
Therapy Diagnosis P Patient Pop Disease I Intervention Test C Comparison Gold Standard O Outcome Accuracy
![Page 45: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/45.jpg)
Foreground Questions - Case
Using the PICO model, jot down 1 foreground question with your partner that will help you care for this patient:
A 42 year old woman comes to her primary care practitioner’s office for follow up of her diabetes. She is currently on glyburide 10 mg twice daily. However, her blood sugars still stay elevated. After you see this patient, your attending asks whether you think she should add metformin to her regimen.
Patient - Intervention - Comparison - Outcome
![Page 46: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/46.jpg)
Foreground Questions - Therapy
• In type II diabetics, is metformin and glyburide better than glyburide alone at lowering blood sugar?
• Among women with type II diabetes, are there
more instances of low blood sugar events in patients on both metformin and glyburide, compared to glyburide alone?
![Page 47: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/47.jpg)
Sources for Foreground Questions
• MEDLINE • Practice Guidelines • Evidence Based-Databases
– Cochrane Library – ACP Journal Club
![Page 48: 08.11.08: The Information Cycle](https://reader034.vdocument.in/reader034/viewer/2022042700/5566778bd8b42a0f168b4711/html5/thumbnails/48.jpg)
Additional Source Information for more information see: http://open.umich.edu/wiki/CitationPolicy
Slide 21: Rajesh Mangrulkar Slide 23: Rajesh Mangrulkar Slide 36: Rajesh Mangrulkar