Differential Diagnosis Generation

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"How I learned to stop worrying and love the BALM:" a method to developing a differential diagnosis

Text of Differential Diagnosis Generation

  • 1. Differential Diagnosis
    Or How I learned to stop worrying and love the BALM
    Clinton Pong

2. Objectives
Define differential diagnosis
Errors
aka how do you get the right ddx
Develop a systematic, routine method for differential diagnosis generation
The BALM
3. The Challenge: What is a Ddx?
Recognize a collection of signs and symptoms
Recall basic pathophysiology
Restate in terms of disease
Reconnect with the initial complaint
Framing: pre-/post-test probability
Reframing: Reconsidering ddx when there is a progression of unusual natural history
4. How many times have you done this?
Premature closure of diagnosis
Hm, this is the cardio unit and they have chest pain.Duh.Its a heart attack.
The crazy House diagnosis
Chest pain and shortness of breath?!? They could have a worm like Strongyloidesstercoralis that went up their gut into their lungs and then to their bloodstream!
The LI of the MINDNUMBING table of differentials A-Z + 1,2,3,4,5,6,7,8,9,10
5. Cognitive Diagnostic Errors
Examples:
Umm trauma or cancer?
80 years old? I thought you said 18 years old.
Psh.Its just a little ____.
The ___ is (+) so it is ____.
The __ is (-) so it is not __.
Its gotta be a ____.
Errors
Faulty hypothesis generation
Faulty context formulation
Faulty information gathering/processing
Inaccurate assessment of prevalence or severity
Wrong interpretation of test
Overrreliance on clinical axiom
Faulty verification
Premature closure of diagnosis
No-fault errors
6. Many diagnostic errors occur because we try
to fit the data to our hypothesis rather than
fitting the hypothesis to our data.
http://www.flickr.com/photos/epublicist/
7. http://hlwiki.slais.ubc.ca/index.php?title=Long_tail#Impact_in_medicine
http://www.medrants.com/?p=3629
8. House, MD.White board
http://differentialdiagnosi.proboards.com/index.cgi?
9. Occams Razor:Quest for the Holy Parsimony
Plurality should not be posited without necessity.
Pluralitas non estponenda sine necessitate
http://en.wikipedia.org/wiki/William_of_Ockham
10. Sherlock Holmes
"When you have eliminated the impossible, whatever remains, however improbable, must be the truth."
11. DeGowins Quotable:
Disease is a four-dimensional story, which follows the biologic imperatives of its particular pathophysiology in specific anatomic sites as influenced by the unique characteristics of this patient.
Your task is not verbal, but cinematic; construct a pathophysiologic and anatomic movie of the onset and progression of the illness: the words are generated from the images, not the images from the words.
12. Nobody ever needs to know that the instant you see lawyer [on the USMLE] you immediately think:
Scumbag who sleeps with prostitutes and therefore has gonorrhea, syphilis, chlamydia, and herpes.
Itll stay our dirty little secret.
http://www.agraphia.net/zac-fact-10-bigot-your-way-to-success/
13. Race/Ethnicity
African Americans have sarcoid and sickle cell.White kids have cystic fibrosis and cant dance.Japanese people have stomach cancer and ninja skills.
Lifestyles
Women are always pregnant. No matter how careful they were.Coke Addicts had an MI (dont smoke crack, kids!)Patients with a swollen knee are female, young, hot, and caught gonorrhea from their last boyfriend.
Etc
http://www.agraphia.net/zac-fact-10-bigot-your-way-to-success/
14. The BALM
By systems
Acute vs Chronic
Local vs Systemic
MEDICINE DOC
Great tier system for starting off your ddx
Where is it?
Will it kill the patient?
What else can it do?
If all else fails, go to the laundry list.
15. Framework
AcutevsChronic
LocalvsSystemic
High Probability Incidence
(the most difficult part of the frame as a medical student)
What is most likely?Rare Common
High Utility Morbidity/Mortality
What do you want to make sure you never miss?Benign Serious
16. The Systems Approach
MEDICINE
Metabolic/Medications
Endocrine
Degenerative
Infection/Ischemia/Infarction
Congenital
Iatrogenic/Idiopathic
Neoplastic
Electrical (Neuro/Psych)
Alternatively,

  • I VINDICATE AID

17. DIRECTION 18. VITAMIN C,DPE organ systems list
Neuro
Lung
CV
GI
Renal/GU/GYN
Heme/ID
Endo
19. The Systems Approach
VITAMIN C, D & E
Vascular
Infection/Ischemia/Infarction
Trauma/Toxin
Autoimmune
Metabolic/Medications
Iatrogenic/Idiopathic
Neoplastic
Congenital
Degenerative
Electrical (Neuro/Psych)
Alternatively,

  • I VINDICATE AID

20. DIRECTION 21. MEDICINEPE organ systems list
Neuro
Lung
CV
GI
Renal/GU/GYN
Heme/ID
Endo
22. By discipline
Hint hint
23. Resources
Groopman, Jerome. How Doctors Think. Mariner Books 2008.
Kassirer, Jerome. Learning Clinical Reasoning. Williams and Wilkins. 1991.
DeGowin's Diagnostic Examination, Ninth Edition (Paperback) by Richard LeBlond (Author), Donald Brown (Author), Richard DeGowin (Author)
http://en.wikipedia.org/wiki/William_of_Ockham
(Heuristics) Bigot your way to Success on the USMLE
http://www.agraphia.net/zac-fact-10-bigot-your-way-to-success/
Separating clinicians from automatons: the long tail
http://doctorrw.blogspot.com/2008/08/separating-clinicians-from-automatons.html