tions compare with alternative, existing treatment approaches, as well as with other health services. Cost effectiveness analysis might be useful, as part of the clinical trial process, to provide potential purchasers and consumers with information that can be used in making financing decisions. To date, such analysis has had few applications in treatment for tobacco and drug abuse. Particular challenges are posed by substance abusers and the nature of the disorder that will need to be addressed, which include the fact that illicit drug and tobacco use often occurs over a number of years, with some effects occurring during the use period, while others may be delayed by many years. In addition, individuals are at risk of relapse (and, perhaps, reinitiated treatment) for a number of years. Another issue is that many of the consequences of drug use of most concern to communities are “externalities”—that is, the affects on the families of smokers and drug users, victims of crimes committed by drug users, and victims of disease transmitted by drug users.

Nonetheless, application of this decision methodology has spread rapidly throughout the general health field. Those responsible for making funding and purchasing decisions in health plans and those developing clinical practice guidelines will have an increasing need for cost effectiveness data.