In-Home Medical Tests : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

A doctor's diagnosis involves evaluation of the patient's medical history and physical examination, often other tests, and sometimes consultation with other medical experts. Further, unlike home testing, professional laboratories must meet quality standards, which provide additional reliability and uniformity to test results.

While no test — OTC or professional — is 100 percent accurate, in a medical setting, Gutman says, "professional, trained people would be expected to interpret test results in a broader context."

The issue of interpreting false results was central to FDA's decision not to grant OTC status to drugs-of-abuse tests, approved for prescription use only. Gutman says scientists are unsure how these tests would affect someone who didn't understand false positives and false negatives. Instead of helping people, such a test might hurt them.

"Drugs of abuse," he says, "have a real punch in terms of emotional impact. The harm from a slight error with, say, a cholesterol test is the user might go out and eat a piece of chocolate cake. But a false positive in a test for drugs of abuse might lead to a person being fired or divorced, or a youngster being falsely accused and punished."

Preventing Problems

A number of tests unavailable over the counter at pharmacies can be bought from medical supply firms without a prescription.

"Consumers should be wary about buying these tests on their own," Gutman says. "Many such products, though nonprescription, are intended for use by trained professionals, or for home use only with medical guidance."

However, interpreting results of the newer OTC tests on pharmacy shelves should not be a problem for consumers. Before FDA will approve OTC sales today, test sponsors must prove that consumers can accurately interpret results.

OTC tests also must be labeled with appropriate warnings. For instance, if a test is not for use by people with diabetes, a large-type warning must state so.

To use in-home tests as safely and effectively as possible, consumers should carefully read the instructions, which FDA makes sure are user-friendly. As Gutman puts it: "Instructions tell how a test works, when it works, when it doesn't, and what to do when it doesn't."

Term Translations

Accuracy is the ability of a test to give consistent results. FDA requires in-home tests to show the same accuracy as professional tests.

False positive is a test result indicating someone has a condition that in fact the person does not.

False negative is a test result that does not identify a condition that is in fact present.

Using Tests Wisely

To use an in-home test as safely and effectively as possible, take these precautions:

• Check the expiration date. If the date is past, don't buy the product. Chemicals in an outdated test may no longer work properly, so the results may not be valid. Don't use a previously purchased test with an expired date.
• Don't leave a temperature-sensitive product in the car trunk or by a sunny car window in hot weather on the trip home from the store. Don't leave it in the car if you go elsewhere.
• Follow the package directions on where to store the product at home.
• Learn what the test is intended to do and what its limitations are. Remember: No test is 100 percent accurate.
• Read the insert to learn how to use the product. Review the instructions and pictures until you fully understand each step.
• Don't guess if something is unclear. Consult a pharmacist or other health professional, or check the instructions for an "800" number.
• Note special precautions, such as avoiding physical activity or certain foods and drugs before testing.
• Follow instructions exactly, including any specimen collection process. Sequence is important. Don't skip a step. If a step to check the test or calibrate an instrument is included, do it.
• When collecting a urine specimen with a container not from a kit, wash the container thoroughly, and rinse out all soap traces — preferably with distilled water, which generally is purer than other bottled or tap water.
• When a step is timed, be precise. Use a stopwatch or a watch that counts seconds.
• Note what to do if the results are positive, negative or unclear.
• Keep accurate records of results.
• If the test depends on color for a step, and you're colorblind, be sure someone who sees color interprets the results.
• If you have questions about the test results or their implications for your health, consult your doctor or other qualified health professional.
• Keep tests containing chemicals, which may be poisonous, or sharp instruments out of the reach of children. Promptly discard used materials as directed.

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.