Journal Club 2010: PL-1 Differential Diagnosis (2)

Facilitator: Conrad Clemens, MD, MPH

Learning Objectives:

Each PL-1 will be able to:

1. Describe the method by which a clinician considers the possible causes of a

patient’s clinical findings before arriving at one diagnosis.

2. List the methods used to create a list of potential diagnoses by:

Possibilistic approach, Probabilistic approach, Prognostic approach, and

Pragmatic approach

3. Selecting tests according to the differential diagnosis:

a. Leading (“Working”) diagnosis—Select specific tests with high likelihood

ratios

b. Alternative (“Rule out”) diagnoses—Select sensitive tests with low

likelihood ratios

c. Other diagnoses (serious, treatable, but very unlikely)—hold off on tests

initially unless time is of the essence in treating the disorder (like our R/O

sepsis babies)

d. Excluded diagnoses—no further tests needed

4. Use & interpretation of likelihood ratios

5. Introduce the importance of pre-test probability

You see a 1 y.o. boy in clinic with a 2 day history of frequent diarrhea, some vomiting, and low grade fever. He is weak with dry lips and you wonder if he might be dehydrated. What symptoms, signs, and laboratory tests will you evaluate to assess his level of dehydration?

Article to be presented by PL-1:

Is this Child Dehydrated? Steiner MJ, DeWalt DA, Byerley JS. JAMA 2004;291:2746-2754.

References:

1. Users’ Guides to the Medical Literature: XV. How to use an article about disease probability for differential diagnosis. Richardson WS, Wilson MC, Guyatt GH, et al. JAMA 1999;281:1214-1219.

2. Review: capillary refill time, abnormal skin turgor, and abnormal respiratory pattern help to detect dehydration in children. Evidence-Based Medicine 2005;10:24.