Journal of General Internal Medicine

, Volume 34, Issue 9, pp 1941–1945 | Cite as

Mind the Base Rate: an Exercise in Clinical Reasoning

  • Paul B. Aronowitz
  • Donna M. Williams
  • Mark C. Henderson
  • Lisa G. Winston
Clinical Practice: Exercises 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...


base 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.


  1. 1.
    Bowen JL. Educational strategies to promote clinical diagnostic reasoning. N Engl J Med. 2006;355(21):2217–2225.CrossRefGoogle Scholar
  2. 2.
    Maserejian NN, Lutfey KE, McKinlay JB. Do physicians attend to base rates? Prevalence data and statistical discrimination in the diagnosis of coronary heart disease. Health Serv Res. 2009;44(6):1933–49.CrossRefGoogle Scholar
  3. 3.
    Minter DJ, Manesh R, Cornett P, Geha RM. Putting schemas to the test: An exercise in clinical reasoning. J Gen Intern Med. 2018.Google Scholar
  4. 4.
    Cunha BA. The clinical significance of fever patterns. Infect Dis Clin N Am. 1996;10(1):33–44.CrossRefGoogle Scholar
  5. 5.
    Kharsany ABM, Karim QA. HIV infection and AIDS in Sub-Saharan Africa: Current status, challenges and opportunities. Open AIDS J. 2016;10: 34–38.CrossRefGoogle Scholar
  6. 6.
    Date KA, et al. Changing patterns in enteric fever incidence and increasing antibiotic resistance of enteric fever isolates in the United States, 2008-2012. Clin Infect Dis. 2016;63:322–329.CrossRefGoogle Scholar
  7. 7.
    Crump JA, Luby SP, Mintz ED. The global burden of typhoid fever. Bull of World Heal Org. 2004;82(5):346–353.Google Scholar
  8. 8.
    Parry CM, et al. Typhoid fever. N Engl J Med. 2002;347(22):1770–1782.CrossRefGoogle Scholar
  9. 9.
    Crump JA, et al. Invasive bacterial and fungal infections among hospitalized HIV-infected and HIV-uninfected adults and adolescents in Northern Tanzania. Clin Inf Dis. 2011;52(3):341–348.CrossRefGoogle Scholar
  10. 10.
    Gilman RH, Terminel M, Levine MM, Hernandez-Mendoza P, Hornick RB. Relative efficacy of blood, urine, rectal swab, bone-marrow, and rose-spot cultures for recovery of Salmonella typhi in typhoid fever. Lancet. 1975;1:1211–1213.CrossRefGoogle Scholar

Copyright information

© Society of General Internal Medicine 2019

Authors and Affiliations

  • Paul B. Aronowitz
    • 1
  • Donna M. Williams
    • 2
  • Mark C. Henderson
    • 1
  • Lisa G. Winston
    • 3
  1. 1.Department of Internal MedicineUniversity of California, Davis School of MedicineSacramentoUSA
  2. 2.Department of MedicineWake Forest School of MedicineWinston-SalemUSA
  3. 3.Division of Infectious DiseasesUniversity of California, San Francisco School of MedicineSan FranciscoUSA

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