The report predicted that widespread use of electronic records could save the United States health care system at least $81 billion a year, a figure RAND now says was overstated. The study was widely praised within the technology industry and helped persuade Congress and the Obama administration to authorize billions of dollars in federal stimulus money in 2009 to help hospitals and doctors pay for the installation of electronic records systems.

"RAND got a lot of attention and a lot of buzz with the original analysis," said Dr. Kellermann, who was not involved in the 2005 study. "The industry quickly embraced it."

But evidence of significant savings is scant, and there is increasing concern that electronic records have actually added to costs by making it easier to bill more for some services.

Officials at RAND said their new analysis did not try to put a dollar figure on how much electronic record-keeping had helped or hurt efforts to reduce costs. But the firm's acknowledgment that its earlier analysis was overly optimistic adds to a chorus of concern about the cost of the new systems and the haste with which they have been adopted.