Health services research is a multidisciplinary field of inquiry, both basic and applied, that examines access to, and the use, costs, quality, delivery, organization, financing, and outcomes of health care services to produce new knowledge about the structure, processes, and effects of health services for individuals and populations.

Several other definitions and descriptions of the field exist, dating back two decades (Flook and Sanazaro, 1973; IOM, 1979, 1991; Steinwachs, 1991). In devising its working definition, the committee built on these earlier statements. The committee believes that its definition captures the essence of the field and provides a base on which to frame its work.

Early health services research was performed by clinicians, economists, and other social scientists who developed an interest in the field. Now, the majority of health services researchers come from such disciplines as biostatistics, clinical sciences, economics, epidemiology, political science, psychology, sociology, and statistics. Other disciplines that contribute to the field include such disparate areas as actuarial science, anthropology, decision theory, demography, engineering, ethics, finance, gerontology, geography, health education, history, law, marketing, medical informatics, nutrition, operations research, and pharmacy. For the purposes of this study, the committee concentrates on researchers—however they were originally trained—whose major professional interest and time commitment is in health services research, as opposed to those researchers trained in any of these disciplines who only occasionally participate in work in this field. In sum, health services research spans a broad, unique view of providers, payers, policymakers, patients, consumers, and communities.

Health services research has accrued an impressive track record in the past quarter-century. Some achievements include:

• Detailed studies of the effects of varying types of health insurance, deductibles, and coinsurance on the utilization and cost of health services (including dental care) and on health status; descriptions of the effect of the lack of health insurance on health status; detailed determinations of the effects of low socioeconomic status on health care outcomes in a broad variety of settings; and demonstration research leading to improvements in medical care for the poor and the aged.
• Detailed studies of the phenomenon of practice variation—a profound mismatch between the epidemiology of disease and the epidemiology of health care—which raises significant questions about the quality of the professional knowledge base and the quality of decisionmaking in medicine.
• Development of tools now widely used in health care financing and reimbursement, including the diagnosis-related groups used in the Medicare prospective payment system and the resource-based relative value scale for setting physician reimbursements.
• Clarification of concepts of health status and functioning, quality of life, patient satisfaction, and psychosocial determinants of behavior and outcome; development of methods and measurement instruments; and application of these products in, for example, investigations of the effects of various home therapy interventions on the ability of people to cope with disabilities and on studies of quality-of-life issues as important indicators of successful rehabilitation.
• Studies of the impact on cost and quality of different kinds of delivery systems, including health maintenance organizations, preferred provider organizations, and other forms of managed care within the United States and internationally.
• Medical effectiveness and cost-effectiveness studies, which have led to expanded health insurance for new services (e.g., alcohol treatment and long-term care) and have documented the oral health benefits of fluoridating drinking water.
• Refinement of concepts and methods of risk adjustment for use in studies to: predict the use of services by a population with certain demographic and health characteristics; estimate appropriate reimbursements for patients with certain characteristics; and compare providers or systems of care on outcomes while controlling for patient differences.