UnitedHealth Group Inc., the largest U.S. health insurer, resolved a conflict-of-interest investigation by New York, agreeing to pay $50 million to fund an independent database on out-of-network reimbursement rates for patients who receive health care from providers outside their insurance network.

Until now, rates were determined by Ingenix Inc., a subsidiary of the health insurer that used erroneous data to figure out how much money consumers should be repaid, the Attorney General’s office said. Insurers often promise to cover as much as 80 percent of the "usual and customary" rate for claims from providers outside their network.

New York Attorney General Andrew Cuomo says Ingenix has been manipulating the numbers so insurance companies pay less. In a just-released report, he contends that Americans have been “under-reimbursed to the tune of at least hundreds of millions of dollars.”

The settlement will have a nationwide impact because UnitedHealth, the biggest health insurer in New York, operates the databases used by the entire industry, through its Ingenix business unit. The deal calls for creation of a new independent database, to be run by a university that is still to be selected.

“The industry reforms that we announce today will bring crucial accuracy, transparency and independence to a broken system,” Cuomo said. “This agreement will keep hundreds of millions of dollars in the pockets of over 100 million Americans.” He also said Tuesday he encouraged other health insurers to follow UnitedHealth’s lead.

The case started in 2006 when Columbia lecturer Mary Jerome complained she was left with tens of thousands of dollars in bills for ovarian cancer treatment, despite having full insurance.