Commentary: improving risk-adjustment models for capitation payment and global budgeting - Methods - response to article by Leida Lamers in this issue, p. 1727

Health Services Research, Feb, 1999 by Mark C. Hornbrook

In the United States, health status surveys are now a part of health plan performance measures (HEDIS for employer groups and Health of Seniors for Medicare). With additional work, these surveys can be expanded to payment applications. The importance of having dual-purpose payment and performance assessment is that it provides countervailing incentives for gaming. Risk adjustment provides an incentive for providers, plans, and sickness funds to encourage their members to deflate their health status scores to make the members appear sicker in order to obtain higher revenues. On the other hand, outcomes assessment provides an incentive for plans and sickness funds to inflate health status scores so that they appear to have healthier enrollees and better outcomes than their competitors.

Therefore, performance (i.e., outcome) assessment and risk adjustment should be treated as complementary policy instruments to provide neutral incentives to survey respondents and providers.

If and when functional health status surveys become a part of routine clinical care and as ordinary as taking vital signs, the incentive for patients to respond truthfully will relate directly to their desire to build a close relationship with their primary care provider(s). The health status survey on which Dr. Lamers' study is based obtained a very good response rate with the sickness fund as the sponsor. With additional work on response rate management and consumer education about the uses of the data for improving quality of care, response rates might be pushed even higher.

Perhaps the most critical policy goal for population health status surveys is the measurement of unmet need. Virtually every health system faces problems managing access: some patients come in too often and others stay away too long. Health status surveys can be part of a comprehensive population-based healthcare system that reaches out to positively identify need and provide service, rather than waiting for sick persons to cross the medical office threshold. One of the findings of this study is that, as more diagnostic information (one versus three years) is added to the risk-adjustment model, less information is contributed by the health survey. This implies that risk-adjustment researchers should examine carefully how to apply FHS survey data in conjunction with diagnosis data. Careful specification of functional form will reduce the problem of multicollinearity between disease vectors and functional health status. For some diseases, for example, FHS should be used as a within-disease severity marker (e.g., congestive heart failure), while in other cases it should be used as a more accurate summary measure of disease burden across a family of diagnoses. Functional health status is a continuum. Research has shown that severe restrictions in functional abilities among aged persons signify multifold increases in health risk (Gruenberg, Kaganova, and Hornbrook 1996). Persons with significant and permanent disabilities are more likely to need continuing multidisciplinary medical care and personal support. The long-term care sector uses functional assessment instruments that focus on the high end of the disability spectrum: basic Activities of Daily Living (ADLs), Instrumental Activities of Daily Living (IADLs), and measures of cognitive function, emotional/behavioral function, and the need for complex assistive devices (e.g., wheelchairs, hospital beds) and medical supports (e.g., dressing changes, ventilatory assistance). This implies that functional health status surveys should be hierarchical, rather than uniform for all respondents, so that persons with poorer functions are guided to provide more information on the nature and severity of their limitations and healthy persons are not burdened with unnecessary questions.