contain costs, payers have also increased their demands for data. Patient data now are used for coverage decisions (e.g., preadmission review) as well as for payment. Cost-containment approaches such as utilization management rely on individual patient data for making short-term decisions; they also rely on aggregated data to make judgments about the effectiveness of medical services in the long-term (IOM, 1989). A recently developed hybrid of quality assurance and cost containment—"value purchasing"—refers to the effort by purchasers, providers, and consumers to promote "the idea of value or quality within the context of cost" (IOM, 1990c:36). Value purchasing requires access to information on both costs and outcomes of care.
The public health arena is also seeking more and better data. The 1988 IOM report on the future of public health recommended that a uniform national data set be established to permit valid comparison of local, state, and national health data to facilitate progress toward achieving national health objectives (IOM, 1988). More recently, the U.S. Public Health Service identified public health surveillance as a primary means of supporting the national disease prevention objectives for the year 2000 (U.S. Public Health Service, 1990). Data are needed to understand the health status of the U.S. population and to develop, administer, and evaluate public health programs aimed at controlling and preventing adverse health events. The Public Health Service report specifically mentions data on (1) mortality, morbidity, and disability from acute and chronic conditions; (2) injuries; (3) personal, environmental, and occupational risk factors associated with illness and premature death; (4) preventive and treatment services; and (5) costs.
The issues of quality, cost, effectiveness, and appropriateness largely frame the questions that today's clinical and health services researchers pursue. Efficacy and safety are no longer sufficient criteria for assessing a technology whose purchasers also want to know (1) whether it is effective and safe outside the controlled environment of clinical trials, (2) whether it is cost-effective, and (3) whether it produces desired outcomes. "[L]ongitudinal observations of natural variations in use and outcomes of economically and clinically important medical technologies in different practice situations" are sought to support utilization management (IOM, 1989:158).11
Late in 1989, the Omnibus Budget Reconciliation Act (P.L. 101–239) established the Agency for Health Care Policy and Research (AHCPR) to enhance "the quality, appropriateness, and effectiveness of health care services, and access to such services, through the establishment of a broad