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The risks of testing for hidden disease

“Just in case” health screening tests can have downsides you may not be aware of.

Have you ever received an offer in the mail to undergo a discount package of “potentially lifesaving” health screening tests? Such for-profit services are typically provided at local clinics and community centers; some companies have their own fleets of mobile screening vans.

Before calling the 800 number to schedule an appointment, talk to your personal physician about the pros and cons of “just in case” health screening to look for signs of hidden disease. It often leads to additional testing and treatment that won’t necessarily benefit you. Unless you understand the potential downsides of for-profit screening, it’s easy to get taken in by false promises.

A healthier lifestyle is one key to lowering health risks. Instead of stepping on the screening bus, step into your walking shoes or stroll down to the farmer’s market and pick up some fresh fruits and vegetables.

Fishing for risks

Companies that market health screening directly to the public offer packages of screening tests that target fear about heart attack or stroke. But what do these allegedly lifesaving tests really offer?

In many cases, not much. As a case in point, consider the U.S. Preventive Services Task Force (USPSTF) July 2014 recommendation concerning carotid ultrasound, a test that uses sound waves to probe the main arteries on either side of the neck for fatty deposits. (The USPSTF issues recommendations on tests and treatments to doctors.)

Men are at higher risk than women for narrowing, or stenosis, in the
carotid arteries, and it’s associated with higher risk of stroke. If you had carotid stenosis, wouldn’t you want to know? The answer might surprise you.

For one thing, carotid stenosis causes no harm unless the narrowing is particularly severe and reduces blood flow. Stenosis can also lead to harm if a fatty deposit breaks open, causing a clot to form and cut off blood supply to part of the brain. The overall chance of stroke occurring in a person with carotid stenosis but no symptoms is 0.5% per year.

For those who choose to clear the blockage, the options on the table are either surgery to directly remove the fatty deposits in the carotid artery or a procedure to insert a special mesh tube, or stent, to widen the narrowed spot and hold it open.

However, these treatments come with a risk for stroke or death of 2% to 3% in the first month, although it later decreases. That means that if you have “silent” (symptomless) carotid stenosis, the chance of harm from treatment in the short term could be four to six times higher than it is in people who choose the usual nonsurgical treatment, which is to take a cholesterol-lowering statin drug as well as a daily low-dose aspirin to prevent clots from forming in the narrowed carotid artery.

Another downside of unnecessary carotid ultrasound testing is that it often leads to additional tests if the first procedure finds anything out of the ordinary. If carotid stenosis is suspected, a man might be in for an MRI and possibly an angiogram. The latter involves injecting dye into the carotid artery and taking an x-ray.

The bottom line is this: the recent USPSTF recommendation “concludes with moderate certainty that the harms of screening for asymptomatic carotid artery stenosis outweigh the benefits.”

What to do

Before being screened with carotid ultrasound, talk to your doctor. Have you ever experienced signs or symptoms of stroke? That would indicate an elevated risk of stroke, and your doctor may recommend that you undergo a carotid ultrasound.

If you decide to forgo tests that seem unlikely to help, that doesn’t mean you should do nothing to reduce your risk of stroke and heart attack. Ask for your doctor’s guidance on controlling your blood pressure and cholesterol. And don’t forget to exercise, eat healthy food, and avoid tobacco.

Cardiovascular screening tests: Should you have them?

The U.S. Preventive Services Task Force (USPSTF) issues recommendations based on research. Here are USPSTF recommendations for several popular cardiovascular risk tests.

Image: Thinkstock

Health condition

Test

USPSTF says

Abdominal aortic aneurysm (bulge in the aorta below the heart)

Abdominal aortic ultrasound

One-time screening in men ages 65 to 75 years who have ever smoked. Men 65 to 75 who never smoked could still consider it after an assessment of risk factors by a physician.

Carotid artery stenosis (clogged neck arteries)

Carotid ultrasound

USPSTF recommends against routine carotid ultrasound screening in otherwise healthy people.

Peripheral artery disease (clogged leg arteries)

Ankle-brachial index

Insufficient evidence to make a recommendation for or against screening for peripheral artery disease in people without symptoms.

Posted by: Dr.Health

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