Health care technology encompasses a wide range of items and services that support clinical practice; it comprises an extensive number of well-established technologies and newly emerging ones. The technologies may include materials from a variety of industries, adaptations of technologies for use in new health settings, replacement of damaged organs and tissue using new or modified procedures and materials, and systems that integrate and monitor information. In what has been called an American "technocopia," such technologies include numerous new and anticipated applications drawn from space and materials technology, the human genome project, and biological research. These may result in genetic engineering applications and new generations of genetic "super drugs." Other technologies may extend preventive and diagnostic techniques to self-care, home, and ambulatory care settings. For example, biosensors and implantable materials for delivering therapies and monitoring the body, as well as the miniaturization of devices, permit treatment to be moved from the hospital to a patient's home or the doctor's office. This flexibility greatly increases the possible range of settings for care and in some cases may decrease the invasiveness of procedures (e.g., new surgical techniques that use small incisions). Other technologies have emerged from work on artificial intelligence systems and from software that assists in monitoring, diagnosis, and therapy—an example is three-dimensional diagnostic imaging. At a multipatient level in the informatics area, health care technologies include microcomputer-integrated clinical management and information systems (Coile, 1990; Misener, 1990).

Ingenious applications such as these seem to hold great promise, and health care technology is often praised for improving medical care. At the same time, it is blamed for fueling the rise in per-capita health care expenditures (Altman and Blendon, 1979; Schwartz, 1987; Ginsberg, 1990). As the costs of health care continue to increase well beyond the rate of inflation in other sectors of the U.S. economy, society has devised methods to control these costs. Yet across-the-board efforts to control the use of procedures and other health care technologies—for example, through administratively imposed caps or cuts in services and programs—have been accompanied by warnings from some health care sectors about the danger these efforts pose to quality and access to care.

Two separate, but related, areas of research—variations research conducted by John Wennberg and others and appropriateness research conducted by Robert Brook and his colleagues—have led policymakers and health services researchers to argue that efforts to control costs should fo-