ProPublica — an independent, nonprofit newsroom that produces investigative journalism in the public interest — obtained four years of prescribing data for Medicare’s drug benefit under the Freedom of Information Act.

It is the first time that data for the program, known as Part D, have been released with prescriber identities. For each prescriber and drug, the data include total claims (including refills), retail cost, days of supply and units (in pills or ounces).

The data cover 2007 through 2010, when more than 1.1 billion prescriptions were written by nearly 1.7 million doctors, nurses and other providers. Nearly three-quarters of those were for patients 65 and older; the rest were for the disabled. To protect patient privacy, the Centers for Medicare and Medicaid Services removed details of the claims if a provider wrote 10 or fewer prescriptions for a specific drug.

Drugs were attributed to providers by the pharmacies that filled their prescriptions. The data do not include prescriptions written in hospitals or during short rehabilitation stays at skilled nursing homes because those are paid under a different part of Medicare. Also excluded are prescriptions for seniors with coverage through employers, some retiree health plans or the Department of Veterans Affairs.

To group and analyze categories of drugs, ProPublica used drug classifications supplied by First Databank, a health information company. For more details about the data and the methodology, go to