One-third of states have little to no competition on the Obamacare exchange markets

As major insurers UnitedHealth, Humana and Aetna -- along with smaller insurers like the Scott & White Health Plan in Texas -- plan to leave the Obamacare insurance markets, the exodus will leave some states without much competition on the exchanges.

A new study by Avalere predicts one-third of the country will have no exchange plan competition in 2017. Seven states: Alaska, Alabama, Kansas, North Carolina, Oklahoma, South Carolina and Wyoming, will have only one carrier per rating region in every region in the state, the Avalere study said.

States divide up their exchange market region into rating areas. Consumers may only purchase plans offered within the rating region in which they reside.

Nearly 55 percent of exchange market rating regions have two or fewer carriers, the Avalere study said.

[Also: Letter shows Aetna warned DOJ it would exit Obamacare markets if merger challenged]

Carrier participation in exchange rate regions has fallen since 2015, which is not surprising given the number of insurers pulling their plans from the market.

In 2015, only 4 percent of exchange rate regions had one or fewer insurers participating, compared to the 36 percent in 2016, Avalere said.

In 2015, 67 percent of rating regions had three or more plans participating, compared to 45 percent in 2016.

[Also: UnitedHealthcare to exit all but 'handful' of Obamacare markets in 2017]

"Lower-than-expected enrollment, a high-cost population, and troubled risk mitigation programs have led to decreased plan participation for 2017," said Dan Mendelson, president of Avalere. "Congress and the Administration can choose to stabilize these markets and re-establish competition--but only through a consensus process that brings in a broader swath of the uninsured."

Once state rating areas are approved by the Department of Health and Human Services, insurers price premiums for the area.

Premiums are rising in 2017, some to double digits, as insurers cite the financial difficulties of covering members who are sicker than projected. Some of the insurers who have withdrawn their product from the market blame the government's lack of a safety net for covering large claims, saying the Centers for Medicare and Medicaid Services needs to revise its risk adjustment model.

[Also: Texas insurer Scott & White Health Plan latest to leave Obamacare market]

According to a Kaiser Health News report, more than eight in 10 consumers on the marketplaces would be protected from rising premiums through government subsidies, because subsidies increase as premiums rise.

To stabilize the Obamacare market, Avalere recommends that the government enhance risk mitigation programs; change current enrollment rules to minimize adverse selection; encourage more individuals to enroll; and make the exchanges more attractive to younger, healthier individuals by changing the age rating provisions, adding lower-cost plan options, or expanding the eligibility for other public programs.

Twitter: @SusanJMorse