Federal health officials will begin monitoring prescription drug usage by millions of Medicare participants in an effort to identify potential safety problems.

The Food and Drug Administration has been under increasing pressure to develop a comprehensive drug surveillance system since the painkiller Vioxx was pulled from the market in 2004 after it was linked to increased risk of stroke and heart attack.

New regulations announced Thursday by the Health and Human Services Department will enable the FDA, states and academic researchers to screen the Medicare claims data. Under the regulation, the Medicare data can be made available in 30 days.

Medicare beneficiaries use an average of 28 prescriptions a year, and those who consider themselves in poor health have an average of 45 prescriptions annually, giving investigators a huge database of health records to tap into.

Officials said they no longer would have to wait years to see how a drug or medical device affects millions of people.

"The era of wait and see is going to become the era of tell me right now," the FDA commissioner, Dr. Andrew von Eschenbach, said.

The Institute of Medicine recommended creation of such a surveillance system in 2006. Personally identifying information will stay inside the Medicare agency and will not be part of the information that the FDA and others look at, officials said.

The FDA primarily relies on physicians and patients to report suspected adverse events. Often, it takes a number of cases before someone at the agency detects a pattern that's worth investigating. Then it conducts an investigation to determine whether the side effects were caused by the drug. At the first hint of trouble, the FDA now will be able to query databases involving tens of millions of patients. It will not only be able to see the medications used, but also whether a patient had lab work done or whether they had to be hospitalized.

The first batch of records the agency will have at its disposal will be from 25 million Medicare beneficiaries. Later, private companies will contribute medical data, Health and Human Services Secretary Mike Leavitt said.

"We're moving from a reactive dependence on voluntary reporting of product safety concerns to a proactive surveillance of medical products currently on the market," Leavitt said.

Officials provided only general details about the cost of enacting what the FDA has labeled the Sentinel Initiative. The agency is hiring more staff, but it won't need a large new computer system, officials said. That's because agencies such as the Centers for Medicare and Medicaid Services will use their own computer systems to do the data-mining. The FDA will simply provide the questions while Medicare's computers supply the answer.

Medicare officials said the program could end up reducing the government's health costs if it can cut down on adverse drug events. The cost of treating preventable adverse events in Medicare comes to about $900 million a year. Also, officials said they will be able to determine when a drug is being inappropriately dispensed to treat certain conditions. By promoting best practices in therapy management, agency officials said they hope to cut down on unnecessary prescription bills.

Dr. Mark McClellan, a senior fellow at the Brookings Institution and a former Medicare administrator, said the new data mining system was actually a good model for maintaining patient privacy. The personal data stays where it was, with an insurer or within a medical practice, or within Medicare. The FDA doesn't need personally identifying information to help it monitor medical practices, he said.

"You don't have to share with the FDA a whole lot of detailed personal information about each case," McClellan said. "What FDA mainly needs to know is what's going on in the population being treated by all these different components of our health care system."

Rep. Rosa DeLauro, D-Conn., said she was glad the FDA was laying the groundwork for the surveillance system. But she said the effort has taken too long and that it's still just in the planning stages.

Von Eschenbach said a pilot project allowing the FDA to look at Medicare data could begin after 30 days.

"We're here today not to simply announce a concept, but to launch what is the next phase for the FDA in post-market surveillance," he said.