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Tuesday, April 24, 2012




     Have you ever been annoyed by your car's 'check engine' light? I mean, have you responded to this light and taken the car in to be checked, only to find there  was nothing really wrong and nothing to be done. [This analogy is provided by Dr. H. Gilbert Welch in his book "Overdiagnosis: Making People Sick in the Pursuit of Health".] The problem now is that your car is so computerized that it even has sensors to detect the function of other sensors. At a certain degree of complexity something has to be at least slightly askew a large fraction of the time. The point that Dr. Welch makes is that getting frequent recommended medical check-ups produces essentially the same result. Your doctor will likely tell you on most of these occasions that "you're 'check engine' light is on" and there's something you have to do to turn it off (despite the often overwhelming odds that everything is just fine). Examples of such situations include the mammogram or chest x-ray with a "suspicious spot," the Pap smear with minor abnormalities like "ASCUS," the stool blood test that is positive (due to hemorrhoids, which are much more common than colon cancer), the blood pressure that is elevated 10 mm Hg more than usual, the freckle that looks just slightly darker than all the other ones, etc. The question for you the patient should be, How often are you metaphorically willing to have your engine checked? It can get to be quite a nuisance. Even more than that, as Dr. Welch points out, it can at times be frankly hazardous to your health.

     Consider this table that he provides for us [his table 2.1]. In it he shows the effects when, hopefully, well-meaning "experts" decide to change the criteria for diagnosis of common conditions. Their imputed motivation for doing this is to catch more people with this condition [i.e., their 'check engine' light is on], so that we might prevent more bad disease outcomes like blindness from diabetes, stroke from hypertension, a heart attack for high cholesterol, and a compression fracture from osteoporosis. The problem is that at the lower range of these physiological variables there are actually a few bad outcomes, but only a very few. As you can see in the table, as you lower the threshold for diagnosing diabetes, hypertension, high cholesterol, and osteoporosis, you are instantly creating literally millions of patients with a "new" disease condition. They are now "sick" and are expected to get "treatment." Only a small percent of such newly diagnosed patients (typically 1-8%) will benefit from this treatment; essentially, a minimum of 92% of the new diagnoses are being subjected to medical scrutiny, testing, and treatment with absolutely no benefit to show for it.


Old criterion
New Criterion

Diabetes: the criterion for diagnosis was changed from a sugar level of 140 down to 126 mg%.
Hypertension: the criterion for diagnosis was changed from 160/100 to 140/90 mm Hg.
High cholesterol: the criterion for  diagnosis was changed from a total cholesterol of 240 mg to 200 mg/dL.
Osteoporosis: The criterion for diagnosis was changed from a “T score” of 2.5 to 2.0

The other problem is that the motivation for these new diagnostic criteria among the "experts" is not always beneficent. Often it is frankly commercial. "The head of the diabetes cutoff panel was a paid consultant to Aventis Pharmaceuticals, Bristol-Myers Squibb, Eli Lilly, GlaxoSmithKline, Novartis, Merck, and Pfizer--all of which make diabetes drugs. Nine of the eleven authors of recent high blood pressure guidelines had some kind of financial ties--as paid consultants, paid speakers, or grant recipients--to drug companies that made high blood pressure drugs. Similarly, eight of the nine experts who lowered the cholesterol cutoff were paid consultants to drug companies making cholesterol drugs. and the first cutoff for osteoporosis was established by a World health Organization panel in partnership with the International Osteoporosis Foundation--an organization whose corporate advisory board consisted of thirty-one drug and medical equipment companies."
     Dr. Welch summarizes the outcomes for persons affected by these new guidelines in this table: 

“If 100 patients are diagnosed on the basis of elevated but near normal levels of a variable and treated for a lifetime, there will be…”
(avoided a heart attack)
TREATED FOR NAUGHT (had a bad outcome despite treatment)
(not helped because they were never going to have a heart attack anyway)
Mildly elevated cholesterol
Mildly low T score for osteoporosis

     This problem also exists with all our fancy new imaging technologies like CT scans and MRIs, as well as for old technologies like plain x-rays and ultrasounds. Here are some typical examples:
  • "Gallstones: In people without any symptoms of gallbladder disease (pain, nausea, or problems with fatty foods, for example), about 10% have gallstones when scanned by ultrasound.
  • "Damaged knee cartilage: In people without knee pain or a history of knee injury, about 40% have meniscal damage in their knees when scanned by MRI.
  • "Bulging discs in the back: In people without any back pain, over 50% have bulging lumbar discs when scanned by MRI."
     And, of course, as I have said in prior blogs, this problem applies to cancer screening. I have already covered prostate cancer, cervical cancer, colon cancer, and breast cancer. Let's take a look at 3 other relatively common cancers--thyroid cancer, melanoma, and lung cancer. 

Thyroid cancer: Thyroid cancer is responsible for about 1,600 deaths each year in the US. The number of cases of thyroid cancer diagnosed each year in the US is much greater       --37,000 cases. This discrepancy is explained by two basic factors:  (1) treatment for the most common thyroid cancers is pretty good; and (2) there is a large portion of thyroid cancers that exist in asymptomatic patients and which is never going to cause any symptoms. In  one autopsy study of 101 older patients who had died of other causes in a hospital, pathologists found clusters of thyroid cancer cells in a full 33% of patients. The researchers in this study concluded that "the smallest forms of thyroid cancer were so common that they should be regarded as normal findings." The moral of this story is that you don't really want your doctor examining your neck (thyroid gland) for lumps because nodules are extremely common (now that we use ultrasound routinely; prevalence is 30-65%), yet death from thyroid cancer is very rare. The United States Preventive Services Task Force recommended against any form of routine thyroid cancer screening in 1996.

Melanoma: There are about 8,400 deaths in the US each year from malignant melanoma. The incidence of melanoma, however, is much higher--around 116,000 cases per year. In recent years there have been many efforts directed at increasing early diagnosis of melanoma and these have resulted in a doubling of the number of cases diagnosed between 1975 and 2005. It would seem like that should be a good thing. But when you look at the annual death rate from melanoma in the same period there has been absolutely no change. This means that all of these extra diagnoses have not reduced the death rate. We have just labelled more people with a diagnosis of melanoma that was going to have no effect on the overall death rate. What we are finding with our increased tendency to biopsy pigmented lesions is that there are many people who have microscopic clusters of abnormal melanin-producing cells who were never going to have any clinical disease from it. Increased screening does not appear to be helping at all. 

Lung cancer: "From a public health perspective, lung cancer is the cancer that warrants the most attention. It's responsible for 162,000 deaths annually in the US. That's more than breast cancer, prostate cancer, melanoma, thyroid cancer, and colon cancer combined. About 215,000 Americans get the diagnosis annually. That means most people diagnosed with lung cancer die from it." Since we know that people who smoke or used to smoke are the ones who have the highest risk for lung cancer, you would think it might make sense to screen this group of patients for lung cancer. If so, you would be wrong.
     Three randomized trials completed in the 1990s showed the screening chest x-rays did not lead to a reduction in lung cancer deaths. "In fact, in two of the studies, screening appeared to cause more deaths." Virtually all cases identified by screening underwent surgery, and the surgery has a significant mortality rate. But this is not the only problem. The other problem is that, after 20 years of follow-up, it appears that approximately 50% of all cancers detected by screening were lung cancers that were small and were never going to cause a problem, yet almost all of these "overdiagnosed" patients underwent surgery.

     Finally, there is the problem of "incidentalomas". This is a new term in medical jargon that refers to abnormal findings on an imaging procedure that was carried out for a purpose unrelated to cancer screening. For example, if a chest CT scan is done for a pulmonary problem, it may also unexpectedly find a "spot" in the liver or kidney. If an ultrasound is done on a carotid artery to assess circulation, it may also see a cyst or nodule in the thyroid gland. 

% of people with an incidentaloma on CT scan
10-year risk of cancer death
Maximal chance that the incidentaloma is a lethal cancer
Chance that the incidentaloma is NOT a lethal cancer
Lung (smokers)
(never smokers)
Thyroid (ultrasound)
< 0.01%
Ø  99.99%

When you reflect on the data in this table, it should be clear to the average person that, if an "incidentaloma" is discovered while some imaging test is done for another purpose, this result should simply be ignored. Otherwise you risk biopsy or surgery for no reasonable expectation of benefit.

COMMENT: I have been citing examples of these kinds of problems for years, but Dr. Welch puts them all together in one easy to read book with tables and diagrams that makes this otherwise dense information very accessible. While he makes a clear case that our traditional (and rather frivolous) approach to screening and diagnosis for these diseases poses significant hazards to your health, he provides less guidance on another approach to health promotion and disease avoidance other than better consumer information. Here is where my approach to prevention through the "Formula for Health" really shines.

    Adopting the 5 simple health habits identified in the "Formula for Health" has been shown in 13 major observational studies and 1 randomized controlled trial to be associated with benefits of the magnitude illustrated in the second poster. This approach requires no screening test, no blood testing or imaging, and creates no risk of overdiagnosis. In fact, it represents the maximum that you can do to improve your overall health. The problem with our modern medical technology is that "overdiagnosis" (with subsequent treatment without benefit) has become a bigger problem than the diseases they were designed to avoid. We have to find another way. A healthy lifestyle (The Formula for Health) is this way.


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