Skip to content
  • About
  • Contact
  • Contribute
  • Book
  • Careers
  • Podcast
  • Recommended
  • Speaking
  • All
  • Physician
  • Practice
  • Policy
  • Finance
  • Conditions
  • .edu
  • Patient
  • Meds
  • Tech
  • Social
  • Video
    • All
    • Physician
    • Practice
    • Policy
    • Finance
    • Conditions
    • .edu
    • Patient
    • Meds
    • Tech
    • Social
    • Video
    • About
    • Contact
    • Contribute
    • Book
    • Careers
    • Podcast
    • Recommended
    • Speaking

When well people seek medical attention in a system designed to care for the sick

George Lundberg, MD
Patient
July 30, 2011
Share
Tweet
Share

Over the past several decades, there has been a shift in the kinds of patients seeking medical care.

The progression has been from sick to early sick to well to worried well to worried sick.

The reasons are beyond the scope of this article. There is a subtle and hidden, but potentially very damaging, factor operating in the diagnostic process when large numbers of well people seek medical attention in a system designed to care for the sick. This factor is the prevalence of disease.

The accuracy of the diagnostic process is ruled by strict arithmetic.

Specificity and sensitivity of the test itself and the prevalence (or pretest probability) of the disease in the population being tested control the accuracy of the process.

Pretest probability means the percent of people being tested who have the disease in question.

A pretest probability of 2% means that 20 people out of 1,000 have the disease. Obviously, 980 people do not have the disease.

At 2% prevalence, using a test with 95% specificity and 95% sensitivity, the rate of false positives will be 72%.

So, 5% of 980 well people will generate 49 false positive tests while 95% of 20 people with the disease will yield 19 true positives.

1,000 people; 49 “wild goose chases,” and only 19 geese caught.

Trouble, especially for the 49.

When the prevalence of a disease decreases, the rate of false positives increases.

Even with a very specific and sensitive test, if the pretest probability in the population is low, there will be more false positives than true positives.

ADVERTISEMENT

False positives lead to one of two things — one, they must be tracked down with additional tests, which are costly and will generate more false positives. Often this leads to unnecessary biopsies and anxiety. This is part of the sad story of mammograms and PSA testing. Or, two, the false positive test result becomes a label of a nonexistent disease and the person carries the burden of a disease he or she does not have. The amount of false diagnoses of any disease, other than heart disease in children, is unknown and generally unstudied.

It is pure arithmetic.

The increase of well people seeking medical care lowers the prevalence of all diseases and increases the rates of false diagnoses.

Beware of this current active Great American Medical Tragedy.

George Lundberg is a MedPage Today Editor-at-Large and former editor of the Journal of the American Medical Association.

Originally published in MedPage Today. Visit MedPageToday.com for more health policy news.

Prev

Why doctors can sometimes be their own worst enemies

July 30, 2011 Kevin 13
…
Next

Why Medicare is the solution to the soaring costs of health care

July 30, 2011 Kevin 18
…

Post navigation

< Previous Post
Why doctors can sometimes be their own worst enemies
Next Post >
Why Medicare is the solution to the soaring costs of health care

ADVERTISEMENT

More by George Lundberg, MD

  • a desk with keyboard and ipad with the kevinmd logo

    Pathologists face a stark career choice

    George Lundberg, MD
  • a desk with keyboard and ipad with the kevinmd logo

    A culture of cover-up has slowed the patient safety movement

    George Lundberg, MD
  • a desk with keyboard and ipad with the kevinmd logo

    Do drugs aid and abet genius or does genius lead to drugs?

    George Lundberg, MD

More in Patient

  • AI’s role in streamlining colorectal cancer screening [PODCAST]

    The Podcast by KevinMD
  • There’s no one to drive your patient home

    Denise Reich
  • Dying is a selfish business

    Nancie Wiseman Attwater
  • A story of a good death

    Carol Ewig
  • We are warriors: doctors and patients

    Michele Luckenbaugh
  • Patient care is not a spectator sport

    Jim Sholler
  • Most Popular

  • Past Week

    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • Here’s what providers really need in a modern EHR

      Laura Kohlhagen, MD, MBA | Tech
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • Why doctors are reclaiming control from burnout culture

      Maureen Gibbons, MD | Physician
    • How community paramedicine impacts Indigenous elders

      Noah Weinberg | Conditions
    • A physician’s reflection on love, loss, and finding meaning in grief [PODCAST]

      The Podcast by KevinMD | Podcast
  • Past 6 Months

    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • Why tracking cognitive load could save doctors and patients

      Hiba Fatima Hamid | Education
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • Here’s what providers really need in a modern EHR

      Laura Kohlhagen, MD, MBA | Tech
    • What the world must learn from the life and death of Hind Rajab

      Saba Qaiser, RN | Conditions
    • How medical culture hides burnout in plain sight

      Marco Benítez | Conditions
  • Recent Posts

    • A physician’s reflection on love, loss, and finding meaning in grief [PODCAST]

      The Podcast by KevinMD | Podcast
    • How fragmented records and poor tracking degrade patient outcomes

      Michael R. McGuire | Policy
    • How New Mexico became a malpractice lawsuit hotspot

      Patrick Hudson, MD | Physician
    • How I learned to stop worrying and love AI

      Rajeev Dutta | Education
    • Understanding depression beyond biology: the power of therapy and meaning

      Maire Daugharty, MD | Conditions
    • Why compassion—not credentials—defines great doctors

      Dr. Saad S. Alshohaib | Physician

Subscribe to KevinMD and never miss a story!

Get free updates delivered free to your inbox.


Find jobs at
Careers by KevinMD.com

Search thousands of physician, PA, NP, and CRNA jobs now.

Learn more

View 2 Comments >

Founded in 2004 by Kevin Pho, MD, KevinMD.com is the web’s leading platform where physicians, advanced practitioners, nurses, medical students, and patients share their insight and tell their stories.

Social

  • Like on Facebook
  • Follow on Twitter
  • Connect on Linkedin
  • Subscribe on Youtube
  • Instagram

ADVERTISEMENT

  • Most Popular

  • Past Week

    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • Here’s what providers really need in a modern EHR

      Laura Kohlhagen, MD, MBA | Tech
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • Why doctors are reclaiming control from burnout culture

      Maureen Gibbons, MD | Physician
    • How community paramedicine impacts Indigenous elders

      Noah Weinberg | Conditions
    • A physician’s reflection on love, loss, and finding meaning in grief [PODCAST]

      The Podcast by KevinMD | Podcast
  • Past 6 Months

    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • Why tracking cognitive load could save doctors and patients

      Hiba Fatima Hamid | Education
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • Here’s what providers really need in a modern EHR

      Laura Kohlhagen, MD, MBA | Tech
    • What the world must learn from the life and death of Hind Rajab

      Saba Qaiser, RN | Conditions
    • How medical culture hides burnout in plain sight

      Marco Benítez | Conditions
  • Recent Posts

    • A physician’s reflection on love, loss, and finding meaning in grief [PODCAST]

      The Podcast by KevinMD | Podcast
    • How fragmented records and poor tracking degrade patient outcomes

      Michael R. McGuire | Policy
    • How New Mexico became a malpractice lawsuit hotspot

      Patrick Hudson, MD | Physician
    • How I learned to stop worrying and love AI

      Rajeev Dutta | Education
    • Understanding depression beyond biology: the power of therapy and meaning

      Maire Daugharty, MD | Conditions
    • Why compassion—not credentials—defines great doctors

      Dr. Saad S. Alshohaib | Physician

MedPage Today Professional

An Everyday Health Property Medpage Today
  • Terms of Use | Disclaimer
  • Privacy Policy
  • DMCA Policy
All Content © KevinMD, LLC
Site by Outthink Group

When well people seek medical attention in a system designed to care for the sick
2 comments

Comments are moderated before they are published. Please read the comment policy.

Loading Comments...