This article originally appeared on ProPublica.

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The Food and Drug Administration issued a rule on Monday that brings new scrutiny to a vast array of critical lab tests, including some popular prenatal genetic screenings, that reach patients without any federal agency checking to ensure they work the way their makers claim.

“This is a significant step forward,” said Peter Lurie, president and executive director of the Center for Science in the Public Interest and a former FDA associate commissioner. These tests have “always been one of the remaining gaping holes in the FDA regulatory structure. And it’s great to see that the agency has taken concrete steps to close it.”

The new rule cites coverage of the issues with lab-developed tests by multiple media outlets and researchers, including ProPublica articles: one that revealed problems with prenatal genetic screenings, popularly known as NIPTs or NIPS and the other on faulty lab-testing for COVID-19 overseen by one company.

The move comes after decades of debate and stalled legislation on LDTs, which also include certain cancer screenings as well as some tests for rare diseases. Because these tests are designed, manufactured and used in a single lab, they escape most federal oversight over marketing and accuracy.

A large coalition of labs, associations and academic medical centers have long pushed back on the prospect of increased FDA involvement in these tests. It would be too onerous, they’ve argued, and it jeopardizes patient access to health services.

One of nearly 7,000 comments submitted in response to the draft rule came from the Association for Molecular Pathology, representing a wide-ranging group of professionals associated with laboratory testing. The FDA’s proposed changes “would result in laboratory professionals being treated as product manufacturers instead of board-certified healthcare providers,” the association’s president wrote, and it would “unequivocally hinder and harm patient care.”

The agency’s hands-off approach dates back to an era when these tests were a relatively small, low-risk sector of the health care system. Now, they are a much bigger player and include high-stakes tests made by commercial companies. While the Centers for Medicare and Medicaid Services reviews lab operations, it doesn’t check whether the tests themselves are clinically valid. The tests aren’t registered with the federal government, so nobody knows how many exist. In 2021, Pew Charitable Trusts estimated that 12,000 labs are likely to deploy them, many of which process thousands a day.

The ProPublica story on prenatal genetic screenings referenced by the FDA revealed how the agency didn’t check the tests before they reached patients or evaluate marketing claims made by the companies that sell them. Companies aren’t required to publicly report when a test gets it wrong, the investigation found, and no federal agency can recall faulty screenings. The story detailed how false positives, false negatives and indeterminate results can have painful consequences for expecting parents. (We also published a guide to the prenatal tests to help families with their questions.)

Our coronavirus investigation showed how a Chicago-based company with state and local contracts in Nevada sold testing services that were unreliable from the start. As it became clear that the lab was telling infected people that they had tested negative for the virus, company officials nonetheless expanded the reach of the lab’s testing. The company declined to comment for ProPublica’s previous stories on these problems.

The rule will go into effect over a four-year period. Within two years, test-makers will be expected to meet registration and listing requirements, among others, which is “a critical part of this rule,” according to Cara Tenenbaum, a former FDA policy adviser whose consultancy has advocated for more active oversight.

“At least knowing what is out there will be huge,” she said in an email.

High-risk tests will need to meet new FDA review requirements before reaching the marketplace starting in November 2027. Moderate-risk and low-risk tests will need to do the same starting in May 2028. It’s unclear how prenatal screening tests would be categorized.

The agency generally will not enforce some or all requirements for certain LDTs, including tests that were first marketed before the rule was issued and have not since been modified or have been modified in certain limited ways.

The agency will also generally not enforce some or all requirements for tests used within the Veterans Health Administration or the Department of Defense, as well as certain tests that meet other narrow conditions.

Nonetheless, the rule marks a massive shift in the FDA’s approach to a sector that touches millions. “The agency cannot stand by while Americans continue to rely on results of these tests without assurance that they work,” FDA commissioner Robert Califf said in an agency news release.

The final rule, he added, aims to “help ensure that important health care decisions are made based on test results that patients and health care providers can trust.”

The FDA tried to rein in the lab tests a decade ago, issuing a draft guidance in 2014. That prompted a two-year backlash from opponents. The agency ultimately dropped it.

Some critics have argued that regulation of LDTs should happen through legislation rather than rulemaking. But many also largely opposed a bipartisan bill in 2022 that came the closest to passing before ultimately being dropped at the end of the year. Later efforts to move a similar bill forward have not gained traction in Congress.

Laurie Menser, chief executive of the Association for Molecular Pathology, said in an emailed statement that the association is “very disappointed” in the new rule.

“It’s unfortunate the agency continues to overstep its authority and bypass the country’s legislative process,” Menser said. “AMP is currently reviewing the different aspects of the rule and assessing the many implications for our members and patient care.”

Lurie, who was closely involved with the FDA effort to address the tests a decade ago, said the rule has been a long time coming. “People had identified this problem a very long time ago, and wanted to take action, but found themselves stymied by opposition,” he said.

“I think that it shows real courage on the part of the agency, as well as commitment to the public health, to take this step,” he added.