Looking inside the nation's medicine cabinet: trends in outpatient drug spending by Medicare beneficiaries, 1997 and 2001.

We examine trends in outpatient prescription drug spending by the Medicare civilian, noninstitutionalized population in 1997 and 2001 using nationally representative data from the Medical Expenditure Panel Survey. We find that the 72 percent increase in drug spending over this period, in excess of price inflation for all goods and services, is primarily attributable to increases in the number of prescriptions per drug user and in the price per prescription. We also find, however, that an increase in the number of users is the primary reason for growth in a number of the fastest-growing subclasses of drugs.