country, and in some markets there is strong competition. They are serving not only the privately insured but also Medicaid programs and a growing share of the Medicare population. Throughout the country, employers and other major purchasers of health services are demanding, and receiving, information on costs and performance that will help them select among plans. Less widely, consumers are seeking information that can help them make informed choices about their health care and health care providers. Individual health plans, consumer groups, and national organizations have developed a variety of reporting systems, often with summary "report cards."
Various initiatives are under way to develop and promote standardized performance indicators. One of these is the Health Plan Employer Data and Information Set, HEDIS, produced by the National Committee for Quality Assurance (NCQA, 1993, 1996). HEDIS is a defined set of performance measures used by employers and managed care organizations to compare health plans on the basis of quality, access and patient satisfaction, delivery of preventive services, membership and utilization, financing, and descriptive management information. In the newer versions, special consideration has been given to identifying measures appropriate for monitoring services for Medicaid beneficiaries. In another national-level activity, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO, 1996) has promulgated standards, the focus of which in recent years has been in keeping with a broader philosophy of performance monitoring and outcomes. More recently, the Foundation for Accountability (FAcct, 1995) is reviewing and recommending other sets of indicators that employers and consumers can use to assess health plan performance. A more specialized set of performance measures has been developed by the American Managed Behavioral Healthcare Association (AMBHA, 1995), specifically for the mental health and chemical dependency services offered by its members.
In many ways these activities build on work being done in the health care sector on quality assessment and quality improvement and on outcomes research. For example, the definition of quality of care formulated by the IOM (1990) directs attention to the importance of good performance in achieving good health outcomes.1 Quality improvement techniques, which have been