Louisiana is one of the five least competitive states among health insurers, with Blue Cross and Blue Shield of Louisiana accounting for 62 percent of the market, according to a new study by the American Medical Association.

“The AMA is greatly concerned that in 41 percent of metropolitan areas, a single health insurer had at least a 50 percent share of the commercial health insurance market,” AMA President Dr. Robert M. Wah said. “The dominant market power of big health insurers increases the risk of anti-competitive behavior that harms patients and physicians, and presents a significant barrier to the market success of smaller insurance rivals.”

The findings were part of “Competition in Health Insurance: A Comprehensive Study of U.S. Markets.” The report looks at the nation’s 388 largest metro areas, the states and Washington, D.C. The study is based on 2012 data from commercial enrollment in fully and self-insured plans, and includes participation in consumer-driven health plans.

Louisiana was the ninth-least competitive health insurance market in the AMA’s 2013 report. The drop to No. 5 from No. 9 was second-largest in terms of competitiveness for health coverage.

In 2014, Blue Cross held 60 percent of the market in the Baton Rouge metro area, 56 percent in the New Orleans metro, 61 percent in Lafayette and 63 percent in Houma-Thibodaux. UnitedHealthcare held the No. 2 spot in each of those markets. In Baton Rouge, United Health had 15 percent of the market; in New Orleans, 18 percent; in Lafayette, 18 percent; and in Houma-Thibodaux, 21 percent.

The least competitive state was Alabama, where Blue Cross and Blue Shield of Alabama, controlled 84 percent of the market statewide.

The most competitive state was Oregon, where Kaiser held the largest share of the market at 18 percent.