(Reuters)—Health insurer Aetna Inc. posted a sharply higher quarterly profit in line with Wall Street's target as its members' low use of health services kept claim costs down.

The No. 3 U.S. health insurer on Wednesday also backed its 2012 profit forecast.

Aetna's fourth-quarter net income rose to $372.6 million, or $1.02 per share, from $215.6 million, or 53 cents per share, a year earlier.

Excluding items, earnings of 97 cents per share matched the average estimate of analysts, according to Thomson Reuters I/B/E/S.

Higher-than-expected taxes and operating costs weighed down otherwise strong results, Goldman Sachs analyst Matthew Borsch said in a research note.

"The underlying earnings power was greater than we expected," Borsch said. "We calculate (fourth quarter) EPS would have been 30 higher with in-line" operating costs and tax rates.

Revenue edged up to $8.57 billion from $8.54 billion a year earlier. Total membership stood at 18.46 million at the end of 2011, roughly unchanged from a year ago.

Aetna spent 80.7% of its premium revenue on medical claims in the quarter, well below the 83% it spent a year ago.

Health insurers have benefited from low claim costs as Americans have delayed doctor visits and medical procedures to save money in the weak economy.

Aetna backed its forecast for earnings of about $5 per share, excluding items, which would be a slight decline from 2011. Analysts were looking for $5.09.

Aetna is the third major health insurer to post fourth-quarter results, after a negative market reaction to reports from larger rivals UnitedHealth Group Inc. and WellPoint Inc. UnitedHealth issued a cautious 2012 forecast, while WellPoint's quarterly profit fell short of Wall Street's target due to high claims in a Medicare plan in California.

At its investor meeting in December, Aetna said it was well positioned to increase revenue 5% a year, on average, over the next few years, driven by growth in its Medicare plans for the elderly and commercial plans for employers.

Through Tuesday, Aetna's shares have risen about 4% this year, outperforming UnitedHealth and WellPoint.