Mind the Base Rate: an Exercise in Clinical Reasoning
In this series a clinician extemporaneously discusses the diagnostic approach (regular text) to sequentially presented clinical information (bold). Additional commentary on the diagnostic reasoning process (italic) is interspersed throughout the discussion.
A 37-year-old man presented to the Emergency Department with 1 month of generalized abdominal pain, fever, chills, and diarrhea. He also noted poor oral intake, anorexia, and an unintentional 20-pound weight loss. He reported four watery bowel movements per day without blood, up until 1 day prior to presentation. For the past 24 h, he had not had any bowel movements or flatus.
This middle-aged man presents with non-bloody diarrhea that is classified as “chronic,” based on duration longer than 30 days. Acute diarrhea (less than 7 days) typically resolves without intervention and does not require extensive evaluation in immunocompetent individuals unless the presentation is severe. Since both fever and weight loss are alarm symptoms...
KEY WORDSbase rate typhoid fever pulse fever dissociation AIDS chronic diarrhea
Compliance with Ethical Standards
Conflict of Interest
The authors report that Dr. William’s spouse is a co-founder and partial owner of a medical device company called Certus Critical Care, Inc. At this time, the company has no devices on the market. All remaining authors declare that they do not have a conflict of interest.