With budgets getting tighter and health care needs growing, it makes sense to funnel shrinking resources to the most effective care. But, as Sharon Begley explains in "The Best Medicine" in the July 2011 issue of Scientific American, finding the best bang for our medical buck would be easier if we used the increasingly important analytical tool of comparative-effectiveness research.

More efficient health care means dispelling some common myths about what "good" care is. Here is a brief explanation of why some of the most prevalent assumptions about medical care in the U.S. and beyond are wrong:

» Next: Myth 1: There is no harm in routine cancer-screening tests

Myth 1: There is no harm in routine cancer-screening tests.

Screening the general population for breast, prostate or other cancers requires weighing the potential benefit of finding a malignant tumor early on—when it is smaller and generally more treatable—against the very real harm of subjecting a lot of people to invasive and/or expensive follow-up procedures that they do not need.

Studies have shown that as many as half of healthy women will receive a false-positive result for breast cancer after 10 years of routine mammogram tests. (A false positive occurs when a diagnostic test tells you that you have a particular ailment, but in reality you do not.) Most of the false-positive group will then have to undergo a more detailed imaging scan and a significant fraction will undergo a biopsy—not to mention dealing with the anxiety of awaiting results.

Mammograms have helped to lower the risk of death from breast cancer. The prostate-specific antigen (PSA) test to screen for prostate cancer, however, cannot even lay claim to such a benefit. Originally developed to help track the recurrence of prostate cancer after the original tumor had already been diagnosed and treated, PSA tests are now widely used as a screening test to pick up unsuspected cases. The only trouble is that two studies (one from the U.S. and one in Europe) have shown that using the PSA test to screen for prostate cancer in this manner does little to decrease death rates in men aged 55 and older. Indeed, the discoverer of PSA has campaigned for years to get people to stop using the PSA test to screen for prostate cancer. (It still makes sense, however, for many men who have a strong family history of the disease or who have actually developed prostate cancer in the past.)

Basically, the more screening tests for different kinds of cancers you undergo, the greater your risk of getting a false-positive result. One study found that half of all people who received at least 14 tests for some combination of prostate, lung, colorectal and ovarian cancer had been given a false-positive result. And men and women with a false-positive test had a one-in-four chance of having to undergo a surgical procedure—with its own attendant risks—to find out that they were okay after all.

» Next: Myth 2: More care is better care

« Previous: Myth 1: There is no harm in routine cancer-screening tests

Credit: Corbis

Myth 2: More care is better care.

When it comes to medical care, you really can have too much of a good thing. Take, for example, the routine use of antibiotics to treat sudden infections of the middle ear (acute otitis media). This condition is the most common reason antibiotics are prescribed for children in the U.S. And yet most ear infections in children will safely clear up on their own within a few days without antibiotic treatment. Treatment for pain relief may be all that is necessary. Antibiotics may be given if symptoms worsen.

Such so-called watchful waiting is good idea, because even something as safe as antibiotics can cause their own set of complications—including chronic ear infection with highly drug-resistant bacteria or diarrhea so severe that hospitalization is required. Indeed, watchful waiting of otherwise healthy children aged six months and up with acute ear infections is one of the options recommended by the American Academy of Pediatrics and the American Academy of Family Physicians. And yet, a 2010 review of prescribing data showed that it is very hard to get physicians to change their habits or parents to accept the idea that it pays to delay antibiotic treatment of acute ear infections.

» Next: Myth 3: Access to medical care is the most important factor in determining how healthy anyone is

« Previous: Myth 1: There is no harm in routine cancer-screening tests

Credit: Laparoscopic Surgery Robot, Nimur/Wikimedia Commons

Myth 3: Access to medical care is the most important factor in determining how healthy anyone is.

Access to health care is only one of several factors that play an important role in determining how healthy people are. Several studies suggest that easily being able to obtain medical care does not play as big a role as education, lifestyle, income and modern housing, along with sanitation (pdf) and vaccination in determining why some folks are healthier than others.

Where the availability of health care makes the biggest difference to the health of any group is when people have regular access to general or primary care clinicians, who are able to take care of most of the medical problems people face most of the time. Good nursing care is particularly important for people with multiple chronic conditions.

» Next: Myth 4: The U.S. has the best health care system in the world

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Myth 4: The U.S. has the best health care system in the world.

According to the scientifically rigorous CONCORD study (published in 2008), the U.S. ranks highest among wealthy industrialized countries in survival from breast and prostate cancer—especially among older people and those with health insurance. U.S. citizens also smoke less, visit the doctor less frequently, and do not spend as much time in the hospital (pdf) as their international counterparts. But the U.S. health care system falls woefully short by comparison with most other countries when it comes to a majority of other major indices. The U.S. spends more both per capita and as a proportion of its total economy on health care than the other 33 members of the Organization for Economic Co-operation and Development (OECD) but gets the poorest return on investment of any of the other countries.

A few concrete examples highlight the surprising shortcomings. The public health achievements of the 20th century mean more people live to be at least 65 years of age than ever before. But in 2006 (the last year of complete OECD health data) the U.S. ranked 28th in continued life expectancy for women who had reached their 65th birthdays. The nation was in 24th place for continued life span for men at age 65. The average older woman in Australia (ranked number six for women), for instance, lived until she was 86.5 years old—or one and a half years longer than her U.S. counterpart. The average older man in Israel (ranked number five for men) lived until just after his 83rd birthday—or about 15 months longer than his U.S. counterpart.

« Previous: Myth 3: Access to medical care is the most important factor in determining how healthy anyone is

Credit: Ear, Nose and Throat Clinic in Taiwan, wm Jams/Flickr