The American Medical Association and several other medical societies have filed a class-action suit against WellPoint Inc., alleging that the nation’s largest insurer participated in an industry-wide scheme to defraud patients and doctors of proper reimbursement through use of UnitedHealth Group‘s Ingenix database.

The suit, filed in Los Angeles federal court, alleges that WellPoint colluded with others to underpay physicians for out-of-network medical services, resulting in patients paying “an excessive portion of the medical bill,” according to the AMA. The AMA filed similar class action lawsuits last month against Connecticut-based Aetna Health Inc. and Philadelphia-based CIGNA Corp.

Nancy H. Nielsen

“Physicians will not tolerate an apparent conspiracy that allows health insurers to play by their own rules without regard to patients, or the legitimate costs required to care for them,” said AMA President Nancy H. Nielsen in a prepared statement.

The suit follows an investigation by the New York attorney general, Andrew Cuomo, that found the Ingenix database was rigged to allow insurers to alter reimbursement rates. Over the last few months, UnitedHealth, CIGNA, Aetna and several New York insurers have severed ties with Ingenix and pledged millions toward a new, independently run database. In February, WellPoint said it would terminate its relationship with the Ingenix reimbursement database and contribute $10 million to the new entity.

Nationwide, WellPoint covers more than 35 million people. In New York, its subsidiary, Empire Blue Cross Blue Shield, covers five million in 10 New York City metropolitan areas and surrounding counties, and its Anthem Blue Cross Blue Shield subsidiary covers Virginia and the Northern Virginia suburbs of Washington, D.C.

The three AMA lawsuits claim that each insurance company conspired with Ingenix on a price fixing scheme that relied on an obscure database to set artificially low reimbursement rates for out-of-network care.

“The AMA’s work to remove the cloak of secrecy from the Ingenix database promises to benefit patients and physicians by reforming the corrupt system for paying out-of-network medical bills,” Nielsen said. “Now that the underlying scheme has been exposed, health insurers are doing the right thing by cutting their ties with the flawed Ingenix database. However, serious damages resulting from prior use of the Ingenix database still need to be addressed.”

In addition to seeking reforms for the invalid payment systems used by Aetna, CIGNA and WellPoint, the AMA and partnered medical societies also seek relief for physicians who were seriously harmed by the insurers’ long-term use of the flawed Ingenix database.

The Litigation Center of the AMA and State Medical Societies is supporting the WellPoint lawsuit in partnership with the California Medical Association, Connecticut State Medical Society, Medical Association of Georgia and North Carolina Medical Society.

No trial date has been set for any of the suits.