Louisiana ranked No. 9 on the American Medical Association’s annual list of states with the lowest level of competition among health insurers.

Blue Cross and Blue Shield of Louisiana had 57 percent of the market, according to the AMA. UnitedHealthCare had the second-largest share at 19 percent.

“In far too many states, one or two insurance companies dominate the market, which can hurt patients, physicians and employers,” said Dr. Ardis Dee Hoven, AMA president. “Without rivals to compete against, a large health insurance company can take advantage of patients by raising premiums and dictating important aspects of patient care.”

Dominant market power increases the risk of anti-competitive behavior by big health insurers and can place physicians at a significant disadvantage since most work in small or solo practices, according to the AMA. A report released in September by the AMA found that almost 60 percent of patient care physicians in the U.S. work in small or solo medical practices.

The other 10 states with the least competitive health insurance markets were Alabama; Hawaii; Michigan; Delaware; Alaska; South Carolina; North Dakota; Nebraska; and Rhode Island.