The Web site for GE Money's CareCredit card lists endorsements from 31 state medical and veterinary associations and 11 national groups, including the American Dental Association, American College of Eye Surgeons, American Society of Plastic Surgeons, American Society of Bariatric Physicians, and American Animal Hospital Association.

The groups that answered our requests for comment said the programs offer useful options for their clients. But Steffie Woolhandler, an associate professor of medicine at Harvard, says, "It's disgraceful for medical associations to be endorsing credit cards for health-care bills because it's a terrible idea for patients." GE Money says dental offices are primary users of CareCredit because dental insurance often covers less than half the cost of treatment.

The ADA's association with GE Money extends to other programs. The ADA says its "Give Kids a Smile" program, which offers screenings and some free dental care, is funded in part through $225,000 in donations from CareCredit, as well as support from chewing-gum manufacturer William Wrigley Jr. Co.