NEW YORK -- Health insurer Aetna ( AET) said fourth-quarter profit fell 57% in the fourth quarter as health care costs increased. Aetna earned $194.7 million, or 42 cents a share, down from $448.4 million, or 87 cents a share. Aetna said profit from operations rose to 96 cents a share from 88 cents. Revenue grew 8% to $7.76 billion. Excluding net realized capital losses, revenue rose 12% to $7.98 billion. Thomson Reuters said analysts expected 94 cents a share on revenue of $7.96 billion. The Hartford, Conn., company said it spent 81.8% of its premium revenue on medical care in the quarter, compared with 80.3% a year ago. Aetna, the third largest U.S. insurer, gained 33,000 medical members in the quarter, finishing the year with 17.7 million.