The spiraling cost of health care has created a health care crisis. Concerns about the appropriate use of expensive medical technologies have been heightened by health services research studies that demonstrate widespread and dramatic geographic variability in the use of tests and procedures. The Agency for Health Care Policy and Research has funded 14 Programmed Outcome Research Teams (PORTs) targeted at specific disease entities. The PORT in ischemic heart disease is examining 2 principal decisions--which patients should undergo cardiac catheterization and, following catheterization, how patients should be treated. The PORT in ischemic heart disease combines information from the literature, 18 databases, and patient preference studies in models examining these 2 decisions. The databases have also been used to develop statistical models that estimate outcomes with different therapies. The benefit of a therapy in a population can be illustrated using an empirically derived, marginal value curve that describes the expected improvement in outcome (e.g., survival) that accrues with additional procedures performed in patients who are most likely to benefit.