The office of New York Attorney General Andrew Cuomo has sent letters asking 3 large health insurers about efforts to set up programs to steer plan members to “highly rated” doctors.

Ranking methods be faulty, especially if they rely solely on claims data, and there is a possibility that health plans could put too much emphasis on the cost of doctors’ services and too little emphasis on the quality of care that the doctors provide, Linda Lacewell, a counsel in Cuomo’s office, writes in the letters.

Another problem is that the carriers seem not be disclosing the data they use to rank doctors even to the doctors themselves, Lacewell writes.

“As a result, doctors and consumers have no ability to bring errors in the rankings to your attention so that they may be corrected,” Lacewell writes.

Lacewell asks the carriers to provide detailed information about their quality programs, and she asks a carrier that has not yet introduced its program in New York, a unit of UnitedHealth Group Inc., Minnetonka, Minn., to refrain from introducing its program in New York without first getting approval from state regulators.