Cost-effectiveness of providing mental health services: the offset effect.

An offset effect occurs when the provision of one type of service leads to a reduction in the use of other related services. This article examines the offset which occurs in medical utilization when mental health services are appropriately provided, especially within prepaid group health care settings. While no study in this area is free of methodologic flaws, the weight of the evidence strongly suggests that, within such settings, the provision of psychiatric input not only provides a service which is indispensible to the concept of comprehensive health care, but also is affordable, in part because of the realization of offset effects.