patient care (Haynes et al., 1989; Saba et al., 1989; Greenes and Shortliffe, 1990). Furthermore, a wide range of information-processing tasks supports patient care, including performing laboratory tests, processing medical imaging data, capturing patient demographic information, filling prescription orders, monitoring quality and appropriateness of services provided, and billing (Martin, 1990).

For the past several years, health care practitioners have faced an explosion in medical knowledge. For instance, MEDLINE⁹ now indexes approximately 360,000 new articles each year from those published in the biomedical literature (National Institutes of Health, 1989). Scientific and technological advances that have contributed to improving the health of the public have also resulted in more complexity in medical practice; clinicians must track ever more numerous diagnoses, procedures, diagnostic tests, clinical processes, devices, and drugs.

The increase in available technologies places an additional burden on physicians: they must read and synthesize the literature and try to decide whether and how new technologies should be applied (Brook, 1989). Often, a gap occurs between the information physicians need and the information available to them at the time of providing patient care. According to Covell and colleagues (1985), an estimated 70 percent of physician information needs are unmet during the patient visit.

In addition to more knowledge, there are more data for health care professionals to manage. The volume and complexity of information per patient have increased owing to a greater number of patient encounters (as patients live longer and experience chronic disease), higher patient acuity of illness (both in and out of hospitals), more kinds of clinical data elements arising from new diagnostic technologies, and developments in the delivery system that result in many patients receiving care at multiple sites. Concomitant with increases in information, however, have been efforts to reduce unit costs of health care provider institutions, which create pressures on health care professionals to be more productive and to see more patients. This paradoxically reduces the time and energy available for the functions associated with management and communication of information. Health care professionals are thus placed in a frustrating, difficult, and perhaps untenable position.