Ricardo Alonso-Zaldivar, AP

Picking a specialist for a delicate medical procedure like a heart bypass could get a lot easier in the not-too-distant future. The government announced Monday that Medicare will finally allow its extensive claims database to be used by employers, insurance companies and consumer groups to produce report cards on local doctors — and improve current ratings of hospitals.

By analyzing masses of billing records, experts can glean such critical information as how often a doctor has performed a particular procedure and get a general sense of problems such as preventable complications. Doctors will be individually identifiable through the Medicare files, but personal data on their patients will remain confidential. Compiled in an easily understood format and released to the public, medical report cards could become a powerful tool for promoting quality care.

"There is tremendous variation in how well doctors do, and most of us as patients don't know that. We make our choices blind," said David Lansky, president of the Pacific Business Group on Health. "This is the beginning of a process to give us the information to make informed decisions." His non-profit represents 50 large employers that provide coverage for more than three million people.

Medicare acting administrator Marilyn Tavenner called the new policy, "a giant step forward in making our healthcare system more transparent and promoting increased competition, accountability, quality and lower costs." But some consumer groups said Medicare is still putting limitations on their access. Early efforts to rate physicians using limited private insurance data has thus far focused on primary care doctors, but Medicare's rich information could provide the numbers to start rating specialists as well, Lansky said. Consumers will see the first performance reports by late 2012, said a Medicare spokesman.

Medicare officials say they expect non-profit research groups in California, Minnesota, Wisconsin, Massachusetts and other states to jump at the chance to use the data. With 47 million beneficiaries and virtually every doctor and hospital in the country participating, Medicare's database is considered the mother lode of healthcare information. Tapping it has largely been forbidden because of a decades-old court ruling that releasing the information would violate the privacy of doctors. Insurance companies tried filling with their own claims data, but their files are nowhere near as comprehensive as Medicare's.

Following appeals from lawmakers of both parties on Capitol Hill, President Barack Obama's healthcare overhaul changed federal law to explicitly authorize release of the information. Medicare followed through in regulations issued Monday. Employer groups welcomed the new policy. Companies will use the data analyses in their annual updates to their insurance plans, but they also want to put report cards directly in the hands of their employees.

Early ratings efforts using insurance company data have lacked sufficient statistical power to rank specialists. The numbers of cases of cancer and serious heart problems in the younger, working-age population simply weren't big enough. The Medicare data could change that, since older people are more prone to chronic illnesses.

Doctors groups fought for years to prevent release of the Medicare data. The American Medical Association argued it could be misleading to untrained consumers. For example, a surgeon who has lots of patients who develop complications may actually be a top practitioner who takes cases that others less skilled would turn away. Lately the medical groups shifted to putting conditions on the use of the data, with some success. For example, Medicare's rule gives individual providers the right to review their information before it is publicly released, and 60 days to challenge it.

Some consumer groups said that particular restriction will make it difficult for them to produce ratings. Unlike employer associations, they don't have economic leverage over doctors. Consumers Union's Health Ratings Center is currently rating hospitals and some medical providers. However, Lisa McGiffert, director of the group's patient safety campaign, said Medicare's review requirement may be too cumbersome for a group like hers.

"These kinds of caveats will lead to fewer users of the data, and fewer communicators to the public," she said. "There's this protectionism about doctors' information that we need to get beyond."