WASHINGTON — Dr. Jeffrey Shuren was adamant: The United States would never cut corners to fast-track the approval of medical devices.

“We don’t use our people as guinea pigs in the U.S.,” Shuren said, holding firm as the new director of the U.S. Food and Drug Administration’s medical devices division.

Again and again in 2011 — four times in all — Shuren was summoned before Congress. Lawmakers accused the agency of being too slow and too demanding in reviewing new devices like heart valves and spinal implants, driving U.S. manufacturers overseas where products faced less rigorous review. Each time, he pushed back.

And yet the next year, Shuren and his team adopted an approach that surprised even some of his closest colleagues: The FDA would strive to be “first in the world” to approve devices it considered important to public health.

The agency’s shift mirrored the talking points of the $400 billion medical device industry — a lobbying behemoth on Capitol Hill — and ushered in a series of changes that critics say have allowed manufacturers to seek regulatory approval for high-risk devices using smaller, shorter, less rigorous studies that provide less certainty of safety and effectiveness.

Under Shuren, annual new device approvals have more than tripled, while warnings letters to device manufacturers about product safety and quality issues have fallen roughly 80 percent, an Associated Press investigation found.

The assortment of medical devices now on the market includes spinal rods that can leave metal shards in children and a nerve-zapping obesity implant that may not work for many patients.

The cheaper and faster medical device approvals began despite multiple, high-profile safety problems involving pelvic mesh, hip replacements and other implants.

An AP analysis of FDA data shows that since 2012, tens of thousands of injury and death reports have been filed in connection with devices that were cleared through a streamlined pathway that minimizes clinical trial testing. The FDA’s database for reporting device problems often includes incomplete, unverified information submitted by manufacturers, physicians, lawyers and patients. Because of these limitations, it’s often unclear whether a device played any role in an injury or death.

In response to questions from the AP, the FDA said its “first in the world” goal was not about a competition with other countries but rather was adopted as part of a strategy that also focused on quickly identifying defective products to ensure U.S. devices “remain safe, effective and of high quality.”

The agency said it has focused on taking steps to reduce the time and cost of device development “that do not compromise our standard of reasonable assurance of safety and effectiveness.”

Warning letters have declined, the FDA said, because the agency is using a new approach that involves fewer warnings but more inspections to oversee companies that violate its rules.

Last week, the FDA announced a new goal to be “consistently first” among the world’s regulatory agencies to identify and address medical device safety issues.

The agency also rejected the idea that Shuren’s approach to regulation has changed over time, saying he has worked for years to improve patient safety.

Still, some current and former FDA officials are worried about the ambition to be first on approvals. They include Dr. Peter Lurie, who calls the agency’s new direction “an invitation to a race to the bottom for scientific standards” seemingly prompted by industry pressure. Lurie held senior posts at FDA from 2009 to 2017 and now heads the nonprofit Center for Science in the Public Interest.

The FDA’s medical device standards are still considered among the highest in the world, requiring “reasonable assurance” of both safety and effectiveness. But by trying to outpace countries with less stringent requirements, Lurie said, the FDA has opened the door to lowering its own standards to achieve its goal.

The FDA’s struggle to find the right mix of regulation and innovation in overseeing more than 190,000 medical devices — from pacemakers to contact lenses to surgical robots — has been chronicled for decades by government inspectors and outside researchers.

For almost as long, the agency has had a symbiotic relationship with industry.

Fees paid by medical device manufacturers for the review of their products now cover about 35 percent of the annual budget of the agency’s Center for Devices and Radiological Health. The last four officials in Shuren’s position have gone on to higher-paid positions in industry.

In addition, Shuren’s wife, Allison, is a former lobbyist who now leads her law firm’s health care practice group and advises medical device clients, among others, on regulatory and legislative issues. The FDA said Shuren passed a “rigorous ethics review process” before assuming his position that addressed potential conflicts of interest. He also recuses himself from FDA matters involving clients represented by his wife or her firm, the agency said.

Joshua Sharfstein, a former FDA deputy commissioner now teaching at Johns Hopkins University, praised Shuren for balancing the competing demands of protecting the public while promptly approving beneficial new devices.

“I don’t think there’s a viable way to be the head of devices and be in open warfare with industry all the time,” he said.

But some who spent years working under Shuren say speeding up product reviews became the clear priority after 2012.

“Basically, it was ‘We need to find ways to get products on the market quicker, faster and we need to figure out how to reduce the premarket data requirements,’ ” said Christy Foreman, an industry consultant who spent 22 years at the FDA, including four years leading its device review office.

The FDA notes that laws passed by Congress require the agency to emphasize the “least burdensome approach” to reviewing new devices. But the agency itself helped fashion those laws, working with industry lobbyists and lawmakers on provisions that effectively limit its ability to request additional evidence from manufacturers.

The philosophy of “acceptable uncertainty” is sometimes the price of making life-saving devices quickly available, according to the FDA. At the same time, it acknowledges its main system for tracking problems is riddled with “incomplete, inaccurate, untimely, unverified or biased data.”

“So instead, you have devices of unknown benefit on the market that still harm patients,” said Dr. Rita Redberg, a prominent medical researcher and cardiologist at the University of California San Francisco. “I do feel that the FDA sees their role as making industry happy and not as much protecting the public health.”

For most of the last century, medical devices were not regulated in the U.S. But a series of high-profile safety problems in the 1970s — including deaths, miscarriages and injuries caused by a contraceptive implant — pushed Congress to intervene.

The laws that resulted are both more complex and less demanding than those governing drugs.

To win FDA approval, for example, most new prescription drugs undergo two large, rigorous clinical studies proving they benefit patients. But most new medical devices enter the market with no clinical trial testing.

Historically, more than 95 percent of FDA-reviewed devices on the market went through a streamlined process in which they need only show that they are “substantially equivalent” to a product already on the market. Typically, only devices considered high-risk, like heart pumps, must demonstrate safety and effectiveness in humans, but even those can sometimes rely on existing scientific data as opposed to new studies.

On Monday, the FDA proposed changes to the streamlined system that would push manufacturers to incorporate more up-to-date technology into their devices. But some of the major reforms could take years to implement.

Some experts have long argued that this fast-track pathway was never intended to be permanent. As framed by Congress in 1976, the system was originally meant to be a temporary way to grandfather in thousands of devices already on the market that weren’t considered high-enough risk to require immediate review. But instead of being phased out, it became mainstream.

The industry contends that flexibility is critical to innovation, allowing manufacturers to quickly and cheaply experiment and improve. An FDA review under that process costs about $11,000, compared to $320,000, under the more rigorous standard.

The result, though, is that some medical products barely resemble the decades-old “predicates” they reference in applying for FDA clearance. And even when old devices have been linked to injuries or death, future products are allowed to reference them for approval because the FDA lacks explicit legal authority to swiftly intervene.

In more than four decades, the FDA has banned only two products — powdered surgical gloves, which caused allergic reactions in patients, and fake hair implants, which caused infections and didn’t work. The agency says its ability to ban products is “bound by federal law” and is essentially limited to devices that are either deceptively marketed or unreasonably dangerous.

The U.S. device system is “basically set up to get things on the market, not to get things off the market,” said Larry Kessler, a University of Washington professor and consultant who worked more than a decade in the FDA’s device center.

The stepped-up approvals and modified enforcement have the endorsement of President Donald Trump and his appointee, FDA Commissioner Dr. Scott Gottlieb, who has highlighted “acceptable uncertainty” as a key concept to “modernize” device regulation.

In September, the FDA began codifying that concept in draft guidelines for manufacturers, which would ease pre-market testing standards for certain devices, in exchange for companies conducting larger follow-up studies, even though the FDA’s own data show that many studies are not completed until five or more years after approval.

The FDA said in a statement that all devices carry a level of uncertainty, even after extensive testing. It said its guidance focuses on “breakthrough” devices, where “it may be appropriate to accept a little more uncertainty,” while still meeting FDA standards.

Lurie and other former regulators worry that the FDA is laying the groundwork for a “sliding scale” of medical evidence that will leave patients even more uncertain about the safety and effectiveness of devices.

“This guidance is basically a ‘come hither’ to industry, inviting them to ask FDA for the lower standards of evidence,” he said.