Physicians Would Order Screening Inappropriately for Ovarian Cancer

Today’s Managing Health Care Costs Indicator is 28%

Likelihood a Physician Would Order Ovarian Cancer Screening Tests
 Nonadherent to Evidence-Based Medicine

Click Image to Enlarge  Source

We’re often overly enthusiastic about screening efforts – because it makes such good intuitive sense that finding a cancer early would be better (and maybe even less expensive) than finding it late.    But screening for especially rare diseases produces many false positives, and screening for diseases where the treatment is of uncertain efficacy leads to many people living longer with a disease only because it was found sooner.  Screening can sometimes increase medical utilization and cost without helping us gain quality adjusted life years. 

The February 7 Annals of Internal Medicine illustrates how difficult it is for physicians to practice evidence based care.  Over a quarter of physicians reported that they would order ovarian cancer screening on low risk women; while almost 2/3 of physicians (65.4%) reported that they would order ovarian cancer screening for women at medium risk of ovarian cancer.  Both the American College of Obstetrics and Gynecology and the US Preventive Health Services  Task Force have recommended against such testing.

Researchers asked a nationally representative sample of  physicians to review one of three clinical scenarios of women of varying ages who were at low, medium, and high risk of ovarian cancer.  The physicians were then asked how likely it would be that they would order CA125 (a blood test) or transvaginal ultrasounds to screen for ovarian cancer.   One in three surveyed physicians believed incorrectly that there was evidence to support using these screening tests in low or medium risk women.  

Factors that made physicians more likely to order this test

-        The patient asked for a screening test

-        The physician believed incorrectly that evidence supported this screening test in this type of situation

-        The physician overestimated patient risk

-        The physician was older

-        The physician was an obstetrician-gynecologist (I might have expected specialists in this field to perform better, not worse)

-        Physician did no clinical teaching

-        Physician had had cancer him or herself

Patients hate uncertainty – and often believe that a noninvasive test couldn’t hurt them.  We doctors should know better, but we don't.  We study Bayes’ Theorem, which demonstrates that doing moderate specificity  on low risk populations produces an overwhelming number of false positives.  But good decision-making requires more explanation.  Further, the patient who has a false alarm is often grateful for our efforts, while we all know of women diagnosed with ovarian (or breast) cancer when they were very young, and many of them die horrible deaths. 

The authors suggest that costs of this excess screening could be as much as $360 million annually across the US.  I suspect that the cost is much higher, because the authors are not counting the downstream tests initiated by the initial false positive from the inappropriate screening test. 

We clearly need more effective professional education around the efficacy of ovarian cancer screening.   The authors note also that patient education has lowered the demand for inappropriate BRCA 1 and BRCA 2 screening women worried about breast cancer, suggesting that patient education could play an important role.

By the way - good news today that colon cancer screening really DOES save lives.  The study reviewed the experience of 2602 patients who had colon polyps removed with rate of death among the general population; patients were tracked as long as 20 years, and the study showed a 53% decrease in rate of death from colon cancer among those who had the polyp removal.

We need physicians to expend more energy to promote colonoscopies, and less energy to promote screening that has not been showed to lengthen or improve life. 

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Internists Step Up to the Plate and Identify Low Value Tests

Today’s Managing Care Indicator is 37

Last May, a group of intrepid oncologists identified five behavior changes and five attitude changes that could allow oncologists to increase the value of health care, largely by not performing certain tests and not administering chemotherapy in certain circumstances.  This is an important effort, encouraged by the Institute of Medicine.

The American College of Physicians, the professional society of internists, has followed suit with an expert panel that identified 37 diagnostic tests that should not be provided to patients.  Each of these tests does little to decrease uncertainty, and many of them are likely to lead to false positives which induce further unnecessary tests.   

The list is at this URL, which is unfortunately behind a paywall. That’s especially unfortunate, because ACP also announced that it would invite physicians and the public to comment on this list.  This is a great example of how to improve a document through crowdsourcing and leveraging the “wisdom of the crowds,” but it will only work if ACP puts the article and the survey outside of the paywall!

Examples of tests that should be avoided:

-       Annual lipid profile for those at low risk and not on therapy

-       Screening tumor marker tests for ovarian cancer in those at low risk

-       Screening for colon and prostate cancer in those over 75

-       Repeating colonoscopy in less than five years for those with benign adenomas

-       Doing too many tests on people who faint but have a normal neurologic exam or patients with migraine headaches

-       Echocardiography for those with innocent-sounding murmurs

-       Many preoperative tests on those at low risk

-       “Screening” EKGs for those at low risk

Some tests that require more judgment:

-       If risk of heart disease is high, go directly to cardiac catheterization with angiography (more invasive.) If risk is low, instead do exercise stress tests. In all instances, do nuclear imaging with the stress test only if the patient cannot exercise or if his/her EKG is sufficiently abnormal that the EKG alone would not give a clear reading.  If the risk is very, very low –don’t do any test at all!

-       For patients with suspected blood clots, do a sensitive blood test for those at low risk, and do an ultrasound test for those at higher risk

Physicians must estimate the pre-test likelihood of a diagnosis before ordering a test. If the pre-test probability is very low, the likelihood of a false positive is often unacceptably high.  If the pre-test probability of a test is very low, the likelihood of a false negative is high, and the physician should often go directly to a more invasive test.   This makes it even more  important to take a careful history and understand underlying risks.  Physicians must be more conversant with the mathematics of test results – and the likelihood of false positives and false negatives based on pre-test probability. See a post from last year on our misguided quest for ‘certainty.’

This kind of evidence-based medicine is anything but a “cookbook.” It takes considerably more meaningful decision-making to follow these rules than to simply do an EKG on every adult.   Exerting this kind of decision-making can lower the cost of health care, and can also increase the meaning of physicians’ work.

An accompanying editorial in the Annals suggests these decision-making rules for physicians to consider before ordering tests (slightly condensed)

·      Did the patient have the test previously?  (If so, is the result likely to be different and can I get the result instead of repeating the test?)

·      Will the test change my care of the patient?

·      What are the probability and consequences of a false positive?

·      Is there short-term danger of not ordering the test right away?

·      Is this primarily for patient reassurance (and if so, is there a better way to reassure the patient?)

This work to identify tests often ordered unnecessarily is an excellent follow-on to the new ACP Ethics Manual, which states:

Physicians have a responsibility to practice effective and efficient health care and to use health care resources responsibly. Parsimonious care that utilizes the most efficient means to effectively diagnose a condition and treat a patient respects the need to use resources wisely and to help ensure that resources are equitably available.

Following these decision-making rules and eliminating these unindicated tests can help lower costs and improve the quality (and value) of health care delivery in the US.

 

Available at URL -but behind paywall. Click image to enlarge.

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Overused MRIs

Today’s Managing Health Care Costs Indicator is 90%

Orthopedist James Andrews thought there was an epidemic of improbable injuries among his patients –and the common denominator was that magnetic resonance imaging (MRI) appeared to be discovering  apparent injuries that just would never matter.   So he scanned the shoulders of 31 major league baseball pitchers who were all pain-free and apparently healthy, and he found that 90% of them had abnormal cartilage, and 87% of them had an abnormal rotator cuff.  Most of us don't use our shoulders like pitchers do - so the 'false positive' rate of MRIs in mortals is probably lower.  But if major league pitchers can pitch with these apparent MRI abnormalities, I can probably do my daily activities without a surgical intervention even if I have a sore shoulder.

Gina Kolata reported this story in today’s New York Times; I’ve looked through PubMed and can’t find reference to the published article.

Other orthopedists quoted said that they virtually never saw a “normal” shoulder or knee MRI – and one patient narrowly averted knee surgery because an orthopedist felt that the diagnosis from the first MRI was too serious based on the patient’s symptoms.  So that orthopedist did a second MRI.

The US has lower utilization of almost every type of service compared to  other developed countries (fewer hospitalizations, office visits, and prescriptions per thousand).   However, high tech imaging is a place where we have both high prices and high utilization. (The only country with higher MRI and CT scan utilization than the US is Japan, where MRIs cost under $100).

We clearly need to start showing more restraint – and not ordering imaging tests where we could answer the question with a clinical exam. We also need to refrain from ordering tests where the pretest probability is so low that the posttest probability that a positive finding was true would still be low.  (See this post for an explanation of this concept)

Unnecessary MRIs are not harmless – and they can often lead to additional invasive therapy (and incremental cost).

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Our quest for certainty makes health care expensive AND exposes us to excess risk.

We intuitively believe that medical diagnostic tests are more likely to banish uncertainty than they really are.

Here’s an example. Many executives have an “executive physical” that includes an exercise stress test to be sure they don’t have coronary artery disease, and many patients pay to have a CT scan to assess coronary artery calcification.

Take a 45 year old executive with a normal blood pressure and a normal cholesterol – his “pretest” probability of having a heart attack or cardiac death in the next 10 years is about 1%.  Here is a link that lets you put in age, gender, blood pressure and cholesterol and calculates risk based on data from the Framingham data.

Imagine 1000 such executives, each with a 1% chance of coronary disease. That means that ten of them will have a heart attack or cardiac death in the next ten years.   If they all had exercise stress tests, with a 70% sensitivity (chance a person with disease will have a positive) and a 90% specificity (chance a positive is a “true” positive” we would have 107 positives – but only 7 of them would be correct.  The overwhelming majority of positive tests would be false positives.   There would be almost 900 negatives, and of these only 3 would be “false” negatives.  

      

This calculation of “posterior probability” is called Bayes Theorem

So – even with a positive test a patient has a low chance of serious cardiac event.  A negative test is much more reliable. However, the executive had a 1% chance of heart disease before the test, while after the test the probability remains about 1/3 as high. 

So – we have more data – but not much more information.  Here is a graphic way to look at this:

Worst of all, there is not evidence that people with no symptoms benefit from invasive therapy to correct cardiac disease.  Even the “lucky” executive whose hidden cardiac disease is discovered through this testing might not be so lucky either!

We desire more information – and insist on more diagnostic tests in a vain effort to banish uncertainty.  Alas, tests done under the wrong circumstances don’t do much to diminish uncertainty.  We want exercise stress tests, mammograms and prostate specific antigen tests, even when our risk of disease is low.  The “cascade” of follow-up tests costs substantial sums (the point of this blog).   This cascade also causes discomfort and anxiety –and sometimes real damage to patients.  

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