November 19, 2007

Health screening: A business run on fear

Osteoporosis. Cancer. Heart attack. Pondering all the random, horrible ways we can get sick is enough to scare anyone stiff.

Hence the proliferation of new health screens--many not covered by insurance--that try to detect disaster early so patients can put up a decent fight. Screens differ from diagnostic tests in that screens are aimed at patients who are not at unusually high risk and exhibit no particularly alarming symptoms.

The problem: Plenty of screens don't really work that well. Many yield lots of false-positive results, which lead to unnecessary (and risky) treatments. Other tests work, though not in time for patients to act, leaving them to a life of endless dread.

"People forget that there are two sides to screening," says Dr Barbara Yawn, director of research at Olmstead Medical Center and a member of the United States Preventive Services Task Force, a government-backed group of health care professionals that study and evaluate health screens. "[Screens] can be beneficial, but there are always other risks."

Here's one horror story, from Dr. Robert Centor, dean of the Hunstville campus at the University of Alabama School of Medicine. Several years ago, during a simple diagnostic chest X-ray, Centor discovered a growth on the lung of one of his patients, who appeared to be in good health. He performed a biopsy to remove the nodule, which turned out to be benign. The patient, however, caught an infection at the hospital and died a few days later.

Despite the risks, health screens are on the rise. While no hard data exist, Yawn says the Preventive Task Force has been asked to review significantly more screenings in the past four years. Dr. David E. Bruns, director of clinical chemistry at the University of Virginia and editor of Clinical Chemistry, says he has seen an increase in the number of tests cited in his medical journal.

Health screening is a business run on fear. "If you find an issue of huge concern to the public and you can market peace of mind, particularly [with regard to] cancer or heart disease, people are willing to buy it," says Dr George Isham, chief health officer of HealthPartners, a health maintenance organization in Bloomington, Minn. "So you see a lot of tests pop up before there's good hard evidence of whether they work or not."

Indeed, the findings by the Preventive Services Task Force are under whelming at best: Of the 60 health screens the group has evaluated, it advises that physicians use only 29--and 10 of those, it says, should be done only at the physician's discretion.

Recommended tests are those that the Task Force believes deliver sufficient preventive value--net of false readings and the risks association with doing further procedures based on them. Some commonly recommended tests include Pap smears (to screen for cervical cancer in sexually active women), high blood-pressure tests, colorectal cancer screens and something called the Factor V Leiden test, which checks a person's predisposition to blood clots.

If a certain disease runs in the family, testing may be a no-brainer. In many other cases, the decision is anything but clear.

"Every advocacy group out there has a slightly different set of recommendations on screenings, so people get confused," says Isham. "Doctors and patients are getting conflicting messages about which tests to use."

Even recommended tests yield a scary number of false readings. Take mammograms, an often promoted and routine exam. According to research compiled by the US Agency for Healthcare Research and Quality, the percentage of false-positive readings is between 7% and 8% for women aged 40 to 59 who took the test. The figure drops to around 4% for women 60 to 79, mainly because the chances of getting breast cancer rise the older women get. If every woman between 40 and 59 in the US had a mammogram, a few million would be fretting unnecessarily over a wrong result.

When it comes to health screens, says Yawn, "it's really important to be honest with patients--what a test is likely to cost in terms of pain, angst and visits to the doctor."

The other problem: Many screens don't discover diseases in time to treat them. "It sounds great to catch cancer early, but it doesn't help unless you can treat it,” says Centor. “You need to be able to change life expectancy and possibly quality of life because of the diagnosis."

Which screens should you think twice about before having?

Perhaps the most dubious are "total body scans." These screens, performed using electron beam computerized tomography, are advertised as a tool that ferrets out cancers, heart disease, aneurysms, you name it. Many radiologists have set up freestanding businesses to peddle these scans.

In reality, the scans are more likely to pick up "incidentalomas"--blips that don't necessarily mean anything but require a follow-up test, says Dr. Roseanne Leipzig, professor of clinical and geriatric medicine at Mount Sinai School of Medicine.

According to recent research by G. Scott Gazelle, director of Massachusetts General Hospital's Institute for Technology Assessment, 90.8% of patients who had a full-body scan got a least one positive finding that led to additional testing. However, only 2% of those actually had a disease. Worse, these tests cost between several hundred and several thousand bucks--and most insurance companies won't pick up the tab.

Prostate-cancer screens create their own dilemmas too. These involve a blood test that looks for unusually high levels of prostate-specific antigens (PSAs). The American Cancer Society suggests men in their 50s take this test yearly (along with a digital rectal exam), but there are two potential flaws.

First, PSA levels generally increase with age and can be inflated because of more benign problems in the prostate, leading to false-positive results. Many men end up having unnecessary biopsies. Second, prostate cancer tends to grow very slowly, which means it might not kill you--or if it does, it will happen much later in life.

The calculation for patients: Skip the test and take your chances, or cut out the cancer early and risk post-surgery downsides like incontinence, impotence and a lot of discomfort.

Then there's the battery of computerized tomography scans. Since 2004, the National Cancer Institute has been conducting trials to see if CT scans (and standard chest X-rays) can reduce mortality in smokers by detecting lung cancer early. Sadly, there's little evidence thus far that supports this technique. In most cases, even with a CT scan, the cancer is found too late.

A full evaluation of the efficacy of CT scans will take at least several more years before any results are found. "These trials require such a large number of people because of the rareness of lung cancer in the overall population," says Isham. "It'll be some years before we have a conclusive answer on that. Good science takes a long time."

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