In-Home Tests Make Health Care Easier

by Food and Drug Administration (FDA)

When it comes to helping people stay healthy, in-home medical tests may be useful. Blood pressure monitors and the new blood cholesterol test, for instance, may play a role in thwarting heart and blood vessel disease. A positive result from a pregnancy test might prompt a woman to go to her doctor sooner, so she gets prenatal care earlier in her pregnancy.

Another device, the home meter for testing blood glucose (sugar) levels can — within seconds — electronically analyze a blood drop from a finger prick, so a person with diabetes knows whether to adjust medicine, exercise or diet.

"By creating the potential for tight control of diabetes, the blood glucose meter has revolutionized this area of medical practice," says the Food and Drug Administration's Steven Gutman, M.D. "It's a cornerstone of modern diabetic therapy." Gutman is acting director of FDA's division of clinical laboratory devices, Center for Devices and Radiological Health, responsible for reviewing many in-home test devices.

More Benefits

Generally, in-home tests provide easy access to medical knowledge about one's health. In some cases, such as monitoring high blood pressure, home testing reduces the number of times a patient must visit a doctor's office or laboratory, thereby reducing medical costs. People also may feel an increased sense of control over their health.

An over-the-counter (OTC) test performs at least one of three functions:

• doctor-recommended monitoring (e.g., blood pressure, for hypertension; blood glucose, for diabetes control; ovulation, for infertility)
• detecting markers for possible health conditions when there are no physical signs or symptoms (blood cholesterol level, for high cholesterol; hidden [occult] blood in stool, for colon or rectal cancer)
• detecting markers for specific conditions when there are physical signs or symptoms (a specific female hormone in urine after a missed period, for pregnancy).

For any in-home test, the manufacturer must convince the agency not only that the test has value (results will benefit consumers), but also that consumers have the knowledge necessary to decide whether testing themselves is appropriate, says Jur Strobos, M.D., J.D., director of FDA's Policy Research Staff. "If the firm does not show that consumers can make this judgment," he says, "we assume the test is for screening without pre-selecting patients. Then, we ask ourselves, is it appropriate for this use?"

Not all tests on the OTC market are equally useful, however, says Philip Phillips, deputy director of FDA's Office of Device Evaluation.

"Some OTC tests that have been marketed for many years," he says, "may not be as useful or acceptable as many consumers believe."

Eye charts, Phillips notes for example, have been sold for decades and are still around in some drugstores, "but you shouldn't rely on them if you think you need eyeglasses or have not had a recent examination." People having eye problems should be examined by a licensed eye-care professional, he says.

Incorrect Results

The more recently approved in-home tests (see chart) are as reliable as professional tests. Still, all tests can generate false positives (indicating someone has a condition that in fact the person does not) or false negatives (a result that does not identify a condition that is in fact present) — particularly if the user doesn't follow directions.

Instead of signifying colon or rectal cancer, a positive result on a test for hidden blood in stool could reflect such factors as bleeding gums or last night's T-bone steak. Or an untrained person may perform the test incorrectly, causing hidden blood in stool to go undetected.

A false negative can occur with a pregnancy test. When a urine sample has a certain level of human chorionic gonadotropin hormone, the test device indicates a probable pregnancy. But pregnant women don't always produce the hormone at the same rate, so a woman could be pregnant but not yet producing enough hormone to prompt the signal from that particular test. Also, levels needed to trigger the signal vary among the different brands of the device. Thus, a test might indicate no pregnancy in a woman who, in fact, is pregnant. If the woman continued certain practices potentially harmful to the fetus, such as smoking, drinking excessively, or taking certain medicines, she might risk her baby's health.

After a negative pregnancy test, therefore, a woman should wait the number of days suggested in the instructions and test again — making sure she's following the instructions properly. If the second test is negative and she's still not menstruating, she should promptly consult her doctor.

In other words, it can be risky for consumers to consider test results as a definite diagnosis. Professional follow-up is needed.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.