Screening Tests – Cumulative Incidence of False Positives

It’s easy to think of medical tests as black and white. If the test is positive, you have the disease; if it’s negative, you don’t. Even good clinicians sometimes fall into that trap. Based on the pre-test probability of the disease, a positive test result only increases the probability by a variable amount. An example:

PSA – To Screen or Not to Screen

You’ve all heard the dramatic testimonials in the media: “I had a PSA test and they found my prostate cancer early enough to treat it. The test saved my life. You should get tested too.” The subject of screening tests is one that confuses the public. On the surface, it would seem that if you

Genewize – Not Wise, Not as Advertised

Genewize http://www.genewize.com/is a new company offering “100% Product Personalization from Your Personal DNA Assessment.” They analyze your DNA to identify certain selected SNPs (single nucleotide polymorphisms) and use the data to tweak the ingredients of the nutritional products they want to sell you (containing everything from vitamins to spinach powder). They previous offered a therapeutic

A Skeptical Look at Screening Tests

I’m an equal opportunity skeptic. I’m skeptical about alternative medicine, pseudoscience, and quackery; but I apply the same standards of skepticism to conventional medicine. I don’t write about conventional medicine so much, because I don’t need to. Science itself is inherently skeptical and scientific medicine is self-criticizing and self-correcting. When better evidence comes along, medical

Are Cardiologists Ordering Too Many CT Angiograms?

A really snazzy new invention allows doctors to see inside their patients’ hearts as never before: the CT angiogram. It produces gorgeous 3-D video images of the beating heart in action. It allows us to see the blood flow through the heart’s chambers and it shows any plaque in the coronary arteries. Cardiologists are understandably

Diagnostic Dilemmas

Sometimes diagnosis is straightforward. If a woman has missed several periods and has a big belly with a fetal heartbeat, it’s pretty easy to diagnose pregnancy. But most of the time diagnosis is much more difficult. Alzheimer’s can’t be diagnosed for sure until the patient dies and you do an autopsy. If only we had

SPECT Scans at the Amen Clinic – A New Phrenology?

Phrenology was a 19th century pseudoscience that claimed to associate brain areas with specific personality traits. It was based on palpating bumps on the skull and was totally bogus. New brain imaging procedures are giving us real insights into brain function in health and disease. They are still blunt instruments, and it is easy and

Ultrasound Screening: Misleading the Public

There is a new industry offering preventive health screening services direct to the public. A few years ago it was common to see ads for whole body CT scan screening at free-standing CT centers. That fad sort of faded away after numerous organizations pointed out that there was considerable radiation involved and the dangers outweighed any

Ultrasound Screening, Fish Oil, and Ear Candles: Sometimes Ignorance is Bliss

I never thought I’d be promoting ignorance!  I’ve always thought the more information, the better; but there are exceptions. I’m going to explain something that is very counterintuitive and grates against every fiber of our truth-seeking skeptical brains. The ad shouts, “Tests That Can Save Your Life… Stroke is America’s third leading killer… Half of

A Skeptical View of SPECT Scans  and Dr. Daniel Amen

Daniel G. Amen, M.D., runs the Amen Clinics, writes books, gives lectures, maintains a Web site, and makes other media appearances. He recommends single photon emission computed tomography (SPECT) to help diagnose and manage cases of brain trauma, underachievement, school failure, depression, obsessive compulsive disorders, anxiety, aggressiveness, cognitive decline, and brain toxicity from drugs or alcohol.

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