Vol. 71 July 15, 2012 When “Yes” Becomes “No” in Medicine

 

“PRIMUM NON NOCERE” – First, do no harm.

This quotation is considered to be the first rule for physicians, but it has a somewhat uncertain origin and a changing definition. The original definition of “harm” became more complicated and variable as medicine accepted the concepts of “risk vs. benefit” and “cost benefit analysis”. Since the values in these concepts are variable, the definition of “harm” has become more variable, more complex, and sometimes more relective of the bias of the definer.

Medicine is both an art and a science, and science, as we know, considers all of its “truths” as tentative. As new data is obtained these truths can change. Here are some recent examples of changes in medical recommendations based on new data AND new elements in“”cost benefit analysis” AND possible bias of the maker of the recommendation.

Men should not be screened for elevated PSA (Prostate Specific Antigen)
The initial excitement about this test for the early (“before symptoms appeared”) diagnosis of prostate cancer has been dissipated by data showing that positive tests (elevated levels of PSA) led to lots of referrals to urologist specialists, lots of biopsies, and lots of invasive surgical and radiation treatment which did NOT result in a reduced death rate or lessened disease burden from prostate cancer. Also, the interventions were associated with a bunch of serious complications.

Prostate cancer is usually an indolent disease. If a man lives long enough it will eventually appear in his body, but will rarely cause death or a heavy disease burden. PSA screening of asymptomatic men who have a normal digital (digital, as in finger) rectal exam and a negative test for occult fecal blood is now considered to cost more (in money, patient inconvenience, and medical complications) than its benefits. The PSA does not identify the less common case of aggressive prostatic cancer at a time that makes earlier treatment more effective.

Women under 50 don’t have to get an annual mammogram.
This 2009 recommendation caused a great deal of controversy because of the long term investments of several “stakeholders” in the mantra “get an annual mammogram to save your life.” But, by 2009, data conclusively showed that in order to save the life of one woman in her 40s from breast cancer, 1,904 women would have to be screened every year for up to 20 years. Because the U.S. Preventive Services Task Force judged that the risks of harm from false positives mammograms, subsequent biopsies, and overly aggressive treatment of indolent lesions that resulted from annual screening outweighed its benefits. Hence, the USPSTF panel’s recommendation that most women ages 40 to 49 need NOT get a routine annual mammogram.

Statins do not prevent fatal heart attacks in healthy people.
Studies in 1999 indicated that lowering cholesterol by taking statins (Lipitor, Zocor, etc.) in people who had had a heart attack reduced subsequent cardiac deaths in those people by 30% and reduced subsequent symptomatic coronary artery disease by 25-60%. This dramatic protective effect of statins in these high-risk patients was extrapolated to people without heart disease or risk factors and by 2008 half of U.S. men between the ages of 65-74 were taking statins. Last year a meta-analysis (a research analysis of a large number of studies) failed to show a reduction of death rates in healthy people taking statins.  “Only limited evidence showed that primary prevention with statins may be cost effective and improve patient quality of life.” (1)  More recent studies documenting the complications and side effects of statin use have also contributed to the change in this recommendation.

Colonoscopy for the prevention of death from colon cancer is no better than, and may be inferior to, flexible sigmoidoscopy.
Not so many years ago your primary physician would perform a screening examination of your lower colon with a flexible sigmoidoscope in his/her office, with just light sedation, no biopsy, and no annoying, rigorous bowel preparation. The reimbursement was modest. Since then, the norm for screening for colon cancer has become a colonoscopy, performed by a gastroenterologist or general surgeon in a hospital or an ambulatory surgical center with sedation heavy enough to warrant the presence of an anthesiologist and associated with an interpretation of the inevitable biopsy by a pathologist. The reimbursement all around is much more substantial.

Both procedures reduce the incidence and mortality of colon cancer, but “as reimbursement moves from fee-for-service to bundled payments for episodes of care, there will be a renewed focus on delivering evidence-based interventions in a manner that optimizes resource use.” (2)

Daily low-dose aspirin does not reduce cardiovascular deaths in healthy people.
Use of aspirin to prevent a subsequent heart attack in people who have already had one DOES reduce their death rate from another heart attack. Extrapolation of this widely accepted fact has prompted many  healthy people with no history of heart disease to take low dose aspirin daily. In yet another meta-analysis of over 100,000 people “at risk for” but not having coronary artery disease, daily aspirin did NOT lower the rate of fatal heart attacks. The rate of non-fatal heart attacks was reduced by 20%, but more importantly the use of aspirin INCREASED the rate of non-trivial bleeding (GI bleeding, stroke, hematuria, and nose bleeding) by 31%, ie. the risks of daily aspirin use outweighed its benefits.
SPOILER ALERT: The study recommends that physicians and patients should decide on a case-by-case basis about whether to continue daily aspirin if you are already taking it. My own physician noted that in several of the international studies in this meta-analysis the dose of aspirin was up to 300 mg a day (one adult aspirin) but that in the U.S. the usual recommended aspirin “low” dose is 81 mg. ( a baby aspirin) daily The higher the dose of aspirin the more likely it is to cause bleeding.

DEET insect repellent is safe to use on anyone over the age of two months.
“The American Academy of Pediatrics states that insect repellents with DEET are safe to use on children as young as two months old.” Apply only once a day, but you can use any concentration from 7% to 25%. The higher concentration isn’t any more effective, but its protection lasts longer. DEET protects against tick bites too.

Statistics NEVER lie, … or can they?
Published medical research produces data that meets statistical standards of “significance” which reassures the reader that the findings are “true”. Meta-analysis studies ( a technique of comparing data results from different studies and treating them as if they are all from the same study) are the current epitome of statistical correlations. The interpretation of statistics, however, is not standardized, and epidemiology (the science of statistics applied to large populations) has been called by some cynics as “the art of lying on a grand scale.”  Here’s an example of the potential pitfalls in interpreting statistics:

700,000 physicians “cause” 120,000 accidental deaths per year for a rate of
.171% accidental deaths per physician per year

There are 1,500 accidental gun deaths per year and 80 million (yes, million) U.S. gun owners for a rate of .0000188% accidental gun deaths per gun owner per year.

THEREFORE, statistically, doctors are approximately
9,000 times more dangerous than gun owners.

We withheld the statistics on ….Lawyers !
for fear the shock would cause people to panic and seek medical attention! (3)

References:
1. Arch Int Med June 2010:170:1024
2. NEJM 366;25 June 21, 2012, pg. 2421
3.  thanks to Bob Harrington for picking this pearl off the web
4. Overdiagnosed: Making People Sick in the Pursuit of Health
H. Gilbert Welch, MD, Lisa M. Schwartz, MD, Steven Woloshin, MD
http://www.beacon.org/

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One Response to Vol. 71 July 15, 2012 When “Yes” Becomes “No” in Medicine

  1. Nice material. I think an understanding of false positives and false negatives really helps to understand why some tests are not appropriate. I am a physician like you. A few patients have had whole body CT scans with lots of false positives. I can not find a reference but I understand there have been deaths as complications of unnecessary biopsies which were prompted by the whole body CT scans. The whole issue of carotid endarterectomy is huge when considering “do no harm”.

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