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Abstract

The purpose of this study is to analyze trends in ADHD medication expenditures globally and among U.S. and OECD countries from 1994 to 2003. We used the IMS Health database and included both branded and generic ADHD medication. The quantity measure was a standard unit (SU) defined by the IMS. Price was defined as the SU average price at the ex-manufacturer level. We examined: change in quantity; change in price; and the residual product of the change in quantity and change in price. During the study decade (1994-2003), the U.S. expenditures increased 594% in real dollars; sales volume rose by 80%; and price increased by 285% in real dollars. In OECD counties, expenditures increased 617%; sales volume 322%, and price 70%. In the U.S., prices increased much faster during the latter half of the study period: 214% increase compared to 23% in the earlier period. The OECD countries saw lower rates of price increase: 48% in 1999-2003 compared to 15% in 1994-1999. It was after 1999 that a number of novel, long-acting ADHD medications became available, and were quickly adopted in the U.S. market to replace the older drugs. This pattern change was a factor in the slowing of sales volume growth and rising price growth rate in the U.S. after 1999. During the study decade, the ADHD medication expenditures dramatically increased; in the U.S. market, price caused much of the increase, while in OECD countries quantity was the most important factor.

Petris Working Paper #100