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Screenings, Overdiagnosis and the Hijacking of Prevention


Dr. Keefe, Keefe Clinic. Tulsa Chiropractor, pain, natural health care.

Screenings, Overdiagnosis and the Hijacking of Prevention

Alan Cassels, MD, states on the first page of his recent book, Seeking Sickness: How the World’s Biggest Pharmaceutical Companies Are Turning Us All into Patients, “Medical screening is a powerful, seductive and highly intuitive thing to do … However, much of what passes for prevention—with medical screening as its centerpiece—is expensive, often misguided, and frequently counterproductive.”

How can this be? After all, we’ve been hearing for years, and sometimes found ourselves repeating, that it’s always better to know what’s happening, that finding abnormalities early is always best, and that the benefits of screenings outweigh their harms. Are we now being asked to accept that these pearls of consensus wisdom are wholly or largely incorrect? And if so, how could we all have been led down this path?

Screenings Primarily Identify Mild Cases or Those with Risk Factors Only

As Gilbert Welch, a primary care physician at a Vermont Veterans Administration hospital and Professor of Medicine at the Dartmouth Institute for Health Policy and Clinical Practice, writes in his equally powerful book, Overdiagnosed: Making People Sick in Pursuit of Health, the problem with screening is that it inevitably identifies as candidates for further diagnosis and therapy many individuals who have mild versions of a condition, along with those who do not have the condition at all and may never manifest it, but are found to have risk factors for the disease in question.

These two categories (mild illness and risk factors in the absence of illness) now constitute the majority of those identified by screening, who are the people least likely to benefit from medical treatment, and thus most likely to have a negative risk-benefit ratio. For many of us who have long advocated strongly for prevention, and who have seen screenings as a key part of disease prevention and health promotion strategies, it may be time to rethink our views.

I have been an enthusiastic proponent of preventive services, including screenings related to heart disease, cancer, diabetes, hypertension, and the other major chronic degenerative diseases of our time. This was a key topic in my most widely disseminated article1 and also was addressed in two later peer-reviewed articles I co-authored.2,3 Moreover, during the years I was involved in direct patient care, and at the institution where I now teach, I have encouraged these screening procedures and taught students to value them. I have seen the information gleaned from screenings as a tool to enable patients to know more about their own health, in the hope that this will guide them toward health-affirming behaviors.

Because we live in a time and place where the major killers are chronic degenerative diseases rather than infectious diseases, it seems logical to find out who is most susceptible to these ailments and then to provide lifestyle-based preventive counseling to fend off their onset for as long as possible. Such an approach is of great value, but primary prevention is increasingly being defined more in terms of early detection of disease and risk factors, and less in terms of the deeper level of prevention found in lifestyle-based counseling. Based on accelerating trends elucidated in four books4-7 by physician-authors that I have recently read, I am growing increasingly worried that screening efforts, however well-intentioned, may serve as an entrenched pipeline for lifelong pharmaceutical therapies that often are not needed and in many cases are harmful. I am still coming to terms with this shift in my perspective.

Is the Prevention Movement Being Hijacked?

I am deeply concerned that prevention, which is very desirable conceptually, is being hijacked for purposes that do not serve public health well. The question is: do mass screenings do more good than harm?

There is no question that screenings help some individuals and save some lives. But how many people are harmed in the process? To flesh this out with real world examples (based on Cassels’ and Welch’s writings), we need to ask the following: (1) how many people will be harmed by false positive or false negative diagnoses? and (2) how many people will need to be treated for many years with, for example, medication for hypertension or osteoporosis, in order to prevent one death, one stroke or one hip fracture? Without those answers, we are flailing in the dark.

Ethical Arguments Pro and Con

The argument in favor of widespread screening is quite straightforward. If we can determine which people in a population are at risk for certain diseases or already have those diseases, as long as effective treatments exist we can deliver those treatments and presumably serve their welfare. Thus, there exists an ethical foundation for population screening as a first step toward further testing of those whose screenings reveal risk factors and subsequent treatment of those found to have frank expression of disease. But the foundation used to justify widespread population screenings rests entirely on whether the benefits outweigh the harms. Absent that, widespread screening is unethical.

The argument against widespread screening programs is that they cast far too wide a net, ensnaring people who are largely healthy, labeling them permanently as patients, subjecting them to a range of invasive diagnostic and therapeutic procedures (including drug therapies), and in the process causing many people both physical and psychological harm. As Dr. Welch puts it in Overdiagnosed, “We are in the midst of an epidemic of overdiagnosis … Diagnosis is a double-edged sword. While it has the potential to help some, it always has a hidden danger: overdiagnosis—the detection of abnormalities that are not destined to ever bother us.”

Screenings and Overdiagnosis

Contrary to widespread and deeply-ingrained belief, more diagnosis and earlier diagnosis does not necessarily mean better health care. It does mean more treatment, but more treatment brings more negative side effects. If a dangerous condition is mitigated or cured in the process, this may be a reasonable trade-off. But when people with mild versions of conditions such as hypertension, cardiovascular disease, or prostate cancer, or risk factors in the absence of such diseases, undergo invasive diagnostic and therapeutic procedures, or are placed on life-long drug prescriptions, the trade-off may be a losing proposition. This is particularly true in cases where only risk factors for disease, rather than disease itself, are identified through screening.

Further complicating the issue, in recent years medical guidelines regarding which patients should be placed on drug therapy (statins for heart disease are Exhibit A) have been repeatedly ratcheted down, by committees with strong ties to drug manufacturers. In late 2013, this reached the point where, as noted in a recent New York Times article, “Dr. Nissen [of Cleveland Clinic in Ohio] entered the figures for a 60-year-old African-American man with no risk factors — total cholesterol of 150, HDL (the good cholesterol) of 45, systolic blood pressure of 125 — who was not a diabetic or a smoker. He ended up with a 10-year risk of 7.5 percent, meaning he should be taking cholesterol-lowering statins despite being in a seemingly low-risk group. Dr. Nissen also calculated the figures for a healthy white man, age 60, and also got a risk factor of 7.5 percent.”

Again, we return to the key question: are we doing more harm than good?

In the case of typical medical, chiropractic, or other practitioners recommending or requiring screenings of all patients for a wide range of conditions, I think we should assume that this is done with the best of intentions. And if there is a serious, sustained effort to pursue diet and exercise-based approaches as the first-line approach, I certainly see screenings as a net positive. But after reading these books by Cassels, Welch and others, along with many related articles8-13 for a public health ethics class I just completed, it is clear to me that no such assumption of public-spirited service should ever be granted to pharmaceutical companies, who provide hundreds of millions of dollars to overtly and covertly support widespread screenings and guidelines that encourage vast increases in drug use. These companies also routinely hide the results of the clinical trials they fund that have determined their drugs to be ineffective or harmful. In some cases, these very drugs yield profits measured in billions of dollars.

For an excellent discussion of current trends on prevention and wellness in chiropractic education and practice, I recommend an excellent 2013 article14 (full text here) by Drs. Cheryl Hawk and Will Evans in Chiropractic and Manual Therapies, as well as their book, Health Promotion and Wellness: An Evidence-Based Guide to Clinical Preventive Services (Lippincott Williams and Wilkins, 2013).15 [Disclosure: I wrote the nutrition chapter in this book.] Because chiropractors recognize the importance of lifestyle-based counseling as the first-line approach, and also recognize the need for medical therapies in more serious cases, the Hawk-Evans approach to clinical preventive services illustrates what I believe is the best available way forward. Needless to say, these two DC-PhD authors are free of drug company conflicts of interest.

The Case of Osteoporosis

Let’s close with an excerpt (Selling Sickness, p. 121) from Dr. Cassels’ chapter on the history of selling osteoporosis drugs, the bisphosphenates such as Fosamax:

“Prior to September 29, 1995, when the U.S. FDA approved Fosamax for the treatment of osteoporosis, that disease was largely unknown to the general public or even to medicine. To understand how we got from there to here is to understand the issue of surrogacy. Intermediate, or surrogate, markers—such as blood pressure, body-mass index, cholesterol levels, intraocular pressure, or, in the case of osteoporosis, bone-mineral density readings—are markers for disease. Your high cholesterol or blood pressure may not be obvious to you, but you don’t want to have a heart attack. In the case of osteoporosis, the reading of your T-score isn’t as important as whether you fracture.

“Many women with low T-scores will never have a fracture in their lives, and many women with ‘normal’ bone density will have fractures. But the point is that a T-score can be measured, assigned a value, and a drug can be given to try to alter that measurement. The goal then, for those with a drug to sell, is to sell the testing first, because without the test you’d have no market. A number of PR firms working in the field of osteoporosis in the mid-1990s were key in reconfiguring osteoporosis from a rare disease that was believed only to strike old ladies to something anyone of any age could get. And in the shadows, funding these activities were pharmaceutical companies like Merck, banking on a big market for its new drug Fosamax.

“The strategy was simple: First, convince women at younger and younger ages that they needed to be screened for this bone-weakening disease, so they were urged through ads and so on to consult their doctors for a bone-density test. Second, the bone- density testing machines needed to be in physicians’ offices, private clinics, and hospitals, so the manufacturers bought and distributed the machines. Third, the tests needed to be paid for, so the PR firms needed to lobby governments to cover the bone-density test. What most people don’t know is that if you define a disease broadly enough, you can capture a large part of the ‘healthy’ population.

“Most also won’t know that drug company executives found themselves at the table at a meeting of the World Health Organization in 1995, helping to create the very definition of osteoporosis. The definition they created was so broad—based on the arbitrary value of the T-score—that it meant that about 50 percent of post-menopausal women in the United States (or about 44 million women) had it. And the message that flowed from the popular press strongly suggested that even the healthiest people should be worried about falling and breaking a hip due to the weakening of their bones.”

The hijacking of prevention continues, with much more than can be contained in this book review. The key take-home message is that for numerous conditions, drugs that may be helpful for a relatively small number of people are being pushed by multinational pharmaceutical companies as appropriate, indeed necessary, for large portions of the population, without evidence that this will do more good than harm. The downside usually becomes known years after millions have taken the drugs, sometimes with disastrous effects.

It is heartening that physician-authors are writing books to make these stories better known. What is needed now is for books like these be read widely, for more people to ask questions, and for policy makers and regulators to do a far better job of protecting the public from predatory drug companies.


1. Redwood D. The health reform moment: peril and possibility in the Obama era. J Altern Complement Med. Jan 2009;15(1):1-3.

2. Globe G, Redwood D, Brantingham JW, et al. Improving preventive health services training in chiropractic colleges part II: enhancing outcomes through improved training and accountability processes. J Manipulative Physiol Ther. Jul-Aug 2009;32(6):453-462.

3. Hawk C, Schneider M, Evans MW, Jr., Redwood D. Consensus process to develop a best-practice document on the role of chiropractic care in health promotion, disease prevention, and wellness. J Manipulative Physiol Ther. Sep 2012;35(7):556-567.

4. Welch G, Schwartz L, Woloshin S. Overdiagnosed: Making People Sick in Pursuit of Health. Boston. Beacon Press. 2011.

5. Moynihan R, Cassels A. Selling Sickness: How the World’s Biggest Pharmaceutical Companies Are Turning Us All into Patients. Vancouver/Toronto/Berkeley. Greystone Books. 2005.

6. Cassels A. Seeking Sickness: Medical Screening and the Misguided Hunt for Disease. Vancouver/Toronto/Berkeley. Greystone Books. 2011.

7. Hadler N. Rethinking Aging: Growing Old and Living Well in an Overtreated Society. Chapel Hill. University of North Carolina Press. 2011.

8. Fletcher SW. Breast Cancer Screening: A 35-Year Perspective. Epidemiologic Reviews. July 1, 2011 2011;33(1):165-175.

9. Foster P, Anderson, CM. Reaching targets in the national cervical screening programme: are current practices unethical? Journal of Medical Ethics. 1998;24:151-157.

10. Rychetnik L, Carter SM, Abelson J, et al. Enhancing citizen engagement in cancer screening through deliberative democracy. J Natl Cancer Inst. Mar 20 2013;105(6):380-386.

11. Shickle D, Chadwick R. The ethics of screening: is 'screeningitis' an incurable disease? J Med Ethics. Mar 1994;20(1):12-18.

12. Skrabanek P. Why is preventive medicine exempted from ethical constraints? J Med Ethics. Dec 1990;16(4):187-190

13. Takala T, Gylling HA. Who Should Know about Our Genetic Makeup and Why? J Med Ethics. 2000;26(3):171-174

14. Hawk C, Evans MW, Jr. A framework for chiropractic training in clinical preventive services. Chiropr Man Therap. 2013;21(1):28.

15. Hawk C, Evans MW. Health Promotion and Wellness: An Evidence-Based Guide to Clinical Preventive Services Philadelphia: Lippincott Williams and Wilkins; 2013.

Daniel Redwood, DC, is a Professor at Cleveland Chiropractic College – Kansas City. He is the Editor-in-Chief of Health Insights Today, Associate Editor of Topics in Integrative Healthcare and serves on the editorial board of the American Chiropractic Association. Dr. Redwood’s website and health policy blog are at