UPDATE 1-U.S. health insurer Anthem's quarterly profit beats estimates

(Adds details on membership)

Jan 31 (Reuters) - Health insurer Anthem Inc reported a higher-than-expected quarterly profit on Wednesday, as it added more members and increased premium rates.

The company, which recorded a one-time benefit of $1.1 billion due to the new U.S. tax law, said enrollment totaled about 40.2 million members at the end of the fourth quarter, an increase of 0.8 percent.

Anthem's results come a day after Amazon.com Inc, Berkshire Hathaway Inc and JPMorgan Chase & Co said they would form a company to cut health costs for hundreds of thousands of their employees, setting up a major challenge to an inefficient U.S. healthcare system.

Anthem said net income rose to $1.23 billion, or $4.67 per share, in the quarter ended Dec. 31, from $368.4 million, or $1.37 per share, a year earlier.

Excluding items, the company earned $1.29 per share, ahead of analysts' average estimate of $ 1.27, according to Thomson Reuters I/B/E/S.

Total operating revenue rose 4.5 percent to $22.45 billion, reflecting premium rate increases, and came in above analysts' estimate of $22.25 billion. (Reporting by Ankur Banerjee in Bengaluru; Editing by Martina D'Couto)