Amerigroup Corp.'s fourth-quarter net income fell 59 percent compared to the final quarter of 2010, when rate hikes and 8 percent enrollment growth helped the health insurer's performance.

The Virginia Beach, Va., company said Friday some key expenses also climbed in the most recent quarter. That countered revenue growth and enrollment gains.

Amerigroup also forecast revenue for this year that topped analysts' expectations.

Amerigroup earned $32.8 million, or 67 cents per share, in the fourth quarter. That compares to earnings of $79.6 million, or $1.59 per share, in the final quarter of 2010. Total revenue increased 10 percent to $1.65 billion from $1.5 billion, as premiums climbed nearly 10 percent to $1.64 billion.

Analysts surveyed by FactSet expected, on average, earnings of 62 cents per share, on $1.62 billion in revenue, for the October-December period.

Amerigroup manages publically funded health programs like Medicaid, the state-federal program that provides coverage for the needy and disabled. It operates in 12 states, including Texas, Florida, New York and New Jersey.

The company said its health benefits expense rose 15 percent in the quarter to $1.39 billion, due in part to rate reductions in Texas. Selling, general and administrative expenses climbed 21 percent to $145.3 million due to litigation, costs related to its Health Plus acquisition and a contribution to the Amerigroup Foundation.

Enrollment grew 4.8 percent to top 2 million people.

For the full year, Amerigroup earned $195.6 million, or $3.82 per share, on $6.32 billion in revenue.

In 2012, Amerigroup expects its revenue to grow about 40 percent on new business in Louisiana and Texas, gains from an acquisition and expansion in existing markets. That would equate to revenue of about $8.85 billion. Analysts expect revenue of about $8.2 billion.

The company did not offer a projection for earnings per share.