It’s one of medicine’s nightmare scenarios — a missed diagnosis that fails to spot a cancer at its most treatable stage, or an incorrect analysis that leads to an unnecessary surgery. Patients rely on diagnostic and screening tools to provide an accurate picture of their health status and to guide treatment decisions. But there’s a growing concern that many of the tests that doctors routinely use may provide misleading or downright false information.
These so-called laboratory-developed tests, or LDTs, are in-house screening and diagnostic tools developed and performed by a single laboratory. Hospitals often use tests devised in their own labs, for example, and doctors ship tissue samples off to these facilities.
[See: 5 Common Preventable Medical Errors.]
While traditional widely marketed tests or kits have been closely regulated by the Food and Drug Administration since the 1970s and go through careful testing to prove their accuracy, lab-developed tests were excused from the oversight because they were typically simple and their use was so limited. But in the years since, rapid and quantum leaps in medical science — the arrival of genetic testing, for example — have spawned a billion-dollar industry that exploits the regulatory loophole to quickly create and sell these new diagnostic tools. The FDA is now pushing for more oversight and plans to issue tougher guidelines later this year.
“Some LDTs have clearly been beneficial,” says Elizabeth Mansfield, deputy director for personalized medicine and molecular genetics in the Office of In-Vitro Diagnostics and Radiological Health at the Food and Drug Administration. “But because we haven’t been regulating them, we don’t know which ones are good and which ones aren’t.” The agency reported last fall that an analysis of 20 of these tests uncovered several examples of inaccurate results that could lead patients to take the wrong drugs or undergo unnecessary surgeries.
[See: 10 Questions Doctors Wish Their Patients Would Ask.]
Industry officials counter that their tests are accurate and even lifesaving, and point out that some FDA-approved tests are already obsolete by the time they get through the lengthy review process. Alan Mertz, president of the American Clinical Laboratory Association, says that “LDTs can be created within a matter of months or even weeks, like the tests for Ebola and SARS, which helps public health laboratories do tests in the middle of these pandemics.” Tests developed to recognize HIV infections greatly helped control their spread and guide treatment, he says.
At least 50,000 LDTs are routinely employed to assess saliva, tissue and blood samples. “LDTs are ubiquitous in hospitals and in health care,” says Dr. Roger D. Klein, medical director of molecular pathology at the Cleveland Clinic. “Where I work, almost everything is an LDT.”
Uses range from screening newborns for a number of illnesses and prenatal testing for Down syndrome to helping women found to have certain mutations make decisions about preventive mastectomy. A few instances of faulty test results have caused women to get mastectomies only to find out later that their mutation had no significance, says Dr. Otis Brawley, chief medical officer of the American Cancer Society. “Because these sorts of things happen, there does need to be some science to justify a test,” he argues.
[See: HIPAA: Protecting Your Health Information.]
Until the oversight situation changes, patients are wise to discuss the chance of error with their doctors before moving forward. Because the FDA-approved tests can become outdated with technology advancing so swiftly, your best bet may be an LDT. “Talk to your doctor and do some research,” advises Klein. “Many LDTs, like ones for oncology applications and heritable diseases, are usually quite accurate.” Many insurers insist that tests are proven, so if yours is unwilling to reimburse for one, he says, that might be a red flag.
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A Raised Bar for Medical Tests originally appeared on usnews.com
