When the federal government began providing billions of dollars in incentives to push hospitals and physicians to use electronic medical and billing records, the goal was not only to improve efficiency and patient safety, but also to reduce health care costs.

But, in reality, the move to electronic health records may be contributing to billions of dollars in higher costs for Medicare, private insurers and patients by making it easier for hospitals and physicians to bill more for their services, whether or not they provide additional care.

Hospitals received $1 billion more in Medicare reimbursements in 2010 than they did five years earlier, at least in part by changing the billing codes they assign to patients in emergency rooms, according to a New York Times analysis of Medicare data from the American Hospital Directory. Regulators say physicians have changed the way they bill for office visits similarly, increasing their payments by billions of dollars as well.

The most aggressive billing — by just 1,700 of the more than 440,000 doctors in the country — cost Medicare as much as $100 million in 2010 alone, federal regulators said in a recent report, noting that the largest share of those doctors specialized in family practice, internal medicine and emergency care.