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There are 75,000 genetic tests available for sale today -- a flood of information that could provide major new insights into health or an unwieldy abundance of information that overloads doctors and drives medical spending higher.

A new study in the journal Health Affairs reveals an explosion of genetic tests over the past four years, with about 10 new ones entering the market each day. Another study, of hundreds of primary-care providers in New York City, found only a third had ever ordered a genetic test or referred a patient for counseling. A minority -- 14 percent -- said they felt confident interpreting results.

The studies point to the huge opportunity and challenges that face the booming business of clinical genomics, which is forecast to grow to a $7.7 billion global industry by 2020. As the cost of sequencing genes has plummeted and tests have proliferated, the knowledge about the best practical uses of such information in the real world has remained relatively nascent. Doctors want better tools to support their decisions.

“If I were a provider trying to figure out what to order, that's where this is in some way the Wild West, because we have so many tests out there,” said Kathryn Phillips, a professor of health economics and health services research at the University of California at San Francisco. “Trying to sort out what to use, when and how much to pay for a test is pretty complicated.”

Phillips led the work to tally the number and type of genetic tests in circulation. Her team limited their search to clinical tests ordered by doctors — leaving out genetic tests marketed directly to consumers.

Of the 75,000 tests identified as of August, many were redundant -- there were only about 10,000 unique test types, because tests offered by different laboratories may test the same genes or a panel of genes. That adds to the difficulties for doctors, who have to figure out which tests are appropriate and worth the price and also make sure they can translate the results into meaningful information for patients.


Health Affairs

Genetic tests for pediatric and rare diseases are growing fastest, followed by prenatal, cancer, hematology and neurology tests.

To Diane Hauser, a senior associate at the Institute for Family Health, the growth in genetic tests shows the complexity of the landscape facing health care providers.

“Ten new tests a day — no one can be expected to master that,” said Hauser, who separately found that most primary-care providers have little confidence in their ability to interpret test results and low trust in companies that offer genetic testing.

Phillips also analyzed claims for genetic tests from commercial insurers to understand the breakdown of spending on these tests. Most of the spending was on prenatal tests, followed by hereditary cancer tests and pharmacogenetic tests used to help choose the optimal drugs for people.

To Phillips, the growth in prenatal testing was a surprise — and a testament to how insurance coverage and acceptance of a new test can drive utilization.

“It was one of the most rapidly adopted and covered tests,” Phillips said. “It got huge market acceptance, and insurers now cover it pretty routinely for high-risk women.”

Hauser and Carol R. Horowitz, a professor of population health science and policy at the Icahn School of Medicine at Mount Sinai, conducted their survey in part because they are concerned about how such decisions by doctors, insurers and companies affect underserved, minority communities.

They decided to focus on how primary-care providers might use genetic testing to understand chronic-disease risk. The providers who took their survey were about to enroll patients with African ancestry in a clinical trial to test for versions of genes that greatly increase risk of kidney failure. These were not hypothetical questions to providers about their feelings about genetic tests but surveys of clinicians whose patients would soon receive genetic test results.

“Slightly more than 1 in 10 had any confidence in interpreting these genetic tests results. Those with more experience of genetic testing, of any kind, did not feel more prepared or more confident,” Horowitz said. “How are we going to help primary-care providers, who are barraged with all these genetic tests — some of which are very actionable and important, and some of which are not.”

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