Minneapolis, Minn. The 4-year-old had an abnormally small head, a condition known as microcephaly, so the child's doctor requested an enclosed bed to prevent the child from rolling off and being injured. The insurer said no.

The 42-year-old woman had shed 200 pounds after bariatric surgery, leaving her with flaps of excess skin that her doctor wanted to remove to prevent infection. The insurer denied the request.

The 3-year-old had dental surgery under general anesthesia. The insurer refused to pay for the anesthesia, despite a state law that required coverage for children that age.

In each instance the insurer was part of UnitedHealth Group, the Minnesota-based health care giant and the second-largest health insurer in the nation.

Disputes between insurers, physicians, patients and state regulators are hardly unusual, and tracking the number of cases filed against UnitedHealth Group or its rivals is difficult. Each state has its own insurance regulator and the National Association of Insurance Commissioners doesn't compile complaints, lawsuits and enforcement actions against insurers.

A recent report by AthenaHealth Inc., in collaboration with the journal Physicians Practice, found that UnitedHealth had a higher denial rate for claims than five other national insurers: Humana, Champus/Tricare, Cigna, Medicare and Wellpoint.

UnitedHealth also took longer on average than five other national insurers - Humana, Aetna, Medicare, Cigna and Wellpoint - to pay physicians for services, according to claims data from 7,000 health care providers analyzed by AthenaHealth, a company that sells financial software for doctors. Overall, the report ranked UnitedHealth third among the seven national insurers for performance.

The wide-ranging federal probe of compensation practices at UnitedHealth, where CEO William McGuire had stock options worth an estimated $1.6 billion at the end of 2005, is serving as fresh fuel for critics who contend that patients suffer when insurers strive to satisfy Wall Street with healthy profits and management with huge paydays.

When insurers cut expenses to raise profits, "the policyholder, in the end, is affected," said Tim Wagner, director of the Nebraska Department of Insurance, who said his department has seen a sharp rise in complaints against UnitedHealth in recent years.

UnitedHealth, which covers 26 million members and expects revenue of $70 billion this year, said the legal and regulatory actions against it are relatively minor in the scope of its everyday activity.

"We do hundreds of millions of transactions," said Mark Lindsay, UnitedHealth's vice president of communications and strategy. "The regulatory and litigation environment is remarkably clear given the controversial nature of things that go on in health care."

Part of that controversy is rising health care costs and the inherent tension between those who sell medical services - doctors and hospitals - and those who buy it: insurers.

Lindsay said conflict is inevitable in a health care system that's going through big changes. For example, he said, some in the medical profession resent a push by insurers to make them start providing consumers with information about cost and quality.

Others agree. "Plans are redefining what they are," said Jeremy Delinsky, a policy director for AthenaHealth. "They don't want to be just claims processors. They're using data for new products to drive patients to providers who do great work at a reasonable cost. ... UnitedHealth is pretty good relative to the other national payers."

UnitedHealth and subsidiary Oxford Health Plans are tangled in litigation in New York City, where Oxford is trying to remove a Queens hospital from its coverage network. The hospital, with a patient mix that is largely low-income immigrants and minorities, is suing to remain in the insurer's network.

In late May, the New York State Department of Health barred UnitedHealthcare of New York, another subsidiary, from enrolling new members until it addresses numerous alleged regulatory deficiencies, including updating financial reports, adding staffing to improve customer relations and responding faster to claims disputes. "We take this matter seriously and are concerned about the length of time it's taken UnitedHealth to address these matters," said department spokesman Robert Kenny.

Earlier in the spring, United Healthcare of Ohio agreed to pay a $125,000 fine and $50,000 in administrative costs to the Ohio Department of Insurance as part of a department investigation into what it called "bid-rigging and inappropriate compensation" between Ohio-licensed insurers and agents. Department director Ann Womer Benjamin called the fine "fairly significant" although UnitedHealth did not admit or deny the allegation that it paid commissions to agents working under contract with other public bodies to select it for insurance coverage.

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