Despite a landmark settlement that was expected to increase coverage for out-of-network care, the nation’s largest health insurance companies have been switching to a new payment method that in most cases significantly reduces reimbursements.

The settlement, reached in 2009, followed New York state’s accusation that the companies manipulated the data they used to price out-of-network procedures, systematically shortchanging the nation’s patients by hundreds of millions of dollars over a decade.

The agreement required the companies to finance an objective database of doctors’ fees that patients and insurers around the country could rely on. Andrew M. Cuomo, then the attorney general, said it would increase reimbursements as much as 28 percent.

It has not turned out that way. Though the settlement required the companies to underwrite the new database with $95 million, it did not obligate them to use it. So by the time the database was finally up and running last year, the same companies, across the country, were rapidly shifting to another calculation method, based on Medicare rates, that usually costs patients substantially more.

“It’s deplorable,” said Chad Glaser, a sales manager for a seafood company near Buffalo, who learned that he was facing hundreds of dollars more in out-of-pocket costs for his son’s checkups with a specialist who had performed a lifesaving liver transplant. “I could get balance-billed hundreds of thousands of dollars, and I have no protection.”

Insurance companies defend the shift toward Medicare-based rates under the settlement, which allowed any clear, objective method of calculating reimbursement. They say that premiums would be even costlier if reimbursements were more generous, and that exorbitant doctors’ fees are largely to blame.

But few dispute that as the nation debates an overhaul aimed at insuring everybody, the new realpolitik of reimbursement is leaving millions of insured families more vulnerable to catastrophic medical bills, even though they are paying higher premiums, co-payments and deductibles.

“They’re not getting what they think they’re paying for,” said Benjamin M. Lawsky, the superintendent of the Department of Financial Services, whose investigators recently found that under the switch, 4.7 million New York state residents — 76 percent of those with out-of-network coverage — are facing reimbursement reductions of 50 percent or more.

The switch “certainly creates the appearance that insurers are trying to end-run the settlement and keep out-of-network payments low,” Lawsky said.

Lawsky, who worked for Cuomo when he was attorney general, is seeking legislation in New York state to require that minimum reimbursements be linked to the new database, known as FAIR Health.

In the 2009 settlement, the insurers did not admit wrongdoing. But they paid to set up FAIR Health as a replacement for Ingenix, a database owned by the insurance giant United Healthcare. Cuomo said Ingenix had consistently understated local “usual and customary” rates — UCRs — that were used nationally to determine how much of a bill was paid when a patient used an out-of-network doctor.

FAIR Health collects billions of bills from insurers to calculate a usual fee for each medical procedure in a given locality. But increasingly, reimbursement is not based on such prevailing rates.

“This shift is mirrored across the country, and the implications in terms of declines in reimbursement are similar,” said Rob Parke, a benefits expert at Milliman, an international actuarial and consulting firm.

The level of reimbursement varies by plan, pegged to benchmarks unknown or misunderstood by many consumers. The traditional benchmark was 80 percent of the UCR, while newer ones mostly range from 140 percent to 250 percent of Medicare rates. That sounds like more, but typically amounts to less, and is drastically below charges in large, unavoidable out-of-network bills.

Depending on the plan, insurers may cover 60 to 80 percent of the benchmark sum; the patient is not only responsible for the rest but also for any outstanding balance. The average emergency bill that insurers reported to state investigators, for example, totaled $7,006, or 1,421 percent of the Medicare rate, and left patients owing an average of $3,778.

FAIR Health’s website allows consumers to compare likely out-of-pocket costs. Glaser, who joined FAIR Health’s consumer advisory board last month after seeing his reimbursement drop, gained his knowledge of health insurance the hard way.

When his son, Ethan, was a baby, doctors said he had a rare liver disease. The family, which was in a health maintenance organization, had to appeal three times to get approval for the out-of-network surgery that saved the boy, now 10. So Glaser was overjoyed two years ago when his employer switched to a preferred provider organization that promised out-of-network coverage. Including premiums and deductibles, he and his employer pay about $14,600 a year for family coverage.

But he discovered that at 150 percent of Medicare rates, it fell far short. In the case of a $275 liver checkup, for example, the balance due was $175, almost three times the patient share under FAIR Health’s customary rate, and three and a half times what it was five years ago under Ingenix.

If Ethan had to repeat the $200,000 transplant, which used some of his father’s liver in 2003, the plan would pay little of the cost under the Medicare formula. Laws protecting consumers from extra out-of-pocket costs apply only to HMOs, which require prior approval to go out of network.

“I wish I could tell you that’s a unique case,” said Sandy Praeger, chairwoman of the health insurance committee of the National Association of Insurance Commissioners and is Kansas’ insurance commissioner. She said consumers were caught in the middle of a battle between insurers demanding discounts and doctors who resist by billing more than they expect to get paid; a conflict intensified because Medicare tilts its payments toward primary care, while most people go out of network for specialists.

“For some things, Medicare is really a poor payer,” she said. “So if that’s the benchmark, that just magnifies the problem.”

United Healthcare referred questions about the switch to the New York Health Plan Association, an insurance trade group, whose president, Paul F. Macielak, said the FAIR Health database was inflated by a subset of physicians. “In an ideal world, everyone would be in network, subject to a contracted rate,” Macielak added.

Doctors, however, complain that insurers are pressuring physicians to join networks by slashing outside reimbursement.

“They want to get them trapped, and then limit care,” said D. Brian Hufford, a lawyer who represented physicians in major class action lawsuits against Ingenix. “They’re simply trying to shift all the risks to the doctors while they take all the profits.”

Mark Wagar, president and chief executive of Empire Blue Cross, which is rapidly switching to Medicare benchmarks, said the concerns were exaggerated, since all but 5 percent of medical care takes place in network.

“It’s the tail wagging the dog,” he said of Lawsky’s proposed legislation to set minimum reimbursement.

Jennifer C. Jaff, founding director of Advocates for Patients with Chronic Illness, uses her own case as an example of the fallout.

Jaff, 54, said she maintained out-of-network coverage with $14,000 in annual premiums because she has Crohn’s disease and is at high risk of colon cancer, which killed three of her grandparents. Last year, after a terrible experience with an in-network doctor in 2010, she said, she returned to a top specialist at NewYork-Presbyterian Hospital who had performed her colonoscopy and upper endoscopy in 2008, coping with scar tissue from her eight abdominal surgeries.

Even with 250 percent of Medicare rates as the benchmark, Jaff owed four times more than she had paid when Ingenix rates were in effect, or $3,137 of a $4,200 doctor’s bill that had increased only 13 percent.

Separately, her insurer, Anthem Blue Cross of Connecticut, paid a $7,806 “facilities fee” to the hospital, about double what the hospital had billed, under a flat rate negotiated by Empire, Anthem’s affiliate in New York.

“Is that not nuts?” Jaff asked.

Wagar, of Empire, defended the practice, saying it kept down premiums overall. An Empire spokeswoman noted that Jaff’s specialist had charged double the median price of a colonoscopy in New York City, which the Medicare formula almost covers.

As for the upper endoscopy, the Medicare formula covered only half the median price; it was halved again, Empire said, to $220 of the $1,860 bill, under new rules that restrict payment when two procedures are done at the same time, to prevent overbilling for patients prepared and sedated only once.

“There’s not a doctor in Manhattan that would have done that endoscopy for $220,” Jaff protested. “They’re not using anything that’s tied to reality.”

© 2012 The New York Times Company