A randomized controlled open trial of population-based disease and case management in a Medicare Plus Choice health maintenance organization.

Introduction: The object of this study was to examine the effect of population-based disease management and case management on resource use, self-reported health status, and member satisfaction with and retention in a Medicare Plus Choice health maintenance organization (HMO).

Methods: Study design consisted of a prospective, randomized controlled open trial of 18 months' duration. Participants were 8504 Medicare beneficiaries aged 65 and older who had been continuously enrolled for at least 12 months in a network model Medicare Plus Choice HMO serving a contiguous nine-county metropolitan area.

What care should be covered?

The answer to the question of what health care services should be covered by a managed care plan is straightforward; the plan should cover whatever the consumer is willing to pay for. From the plan's perspective, the consumer is the payer, that is, the employer who negotiates the plan; not the individual patient whose personal preferences and interests may be quite different. Since managed care organizations contract with payers to arrange for health care services within a defined set of benefits, there is a broader question as well: Within the benefits chosen by the payer, what actually is covered? Criteria for determining "medical necessity," which managed care plans frequently use as the basis for coverage, are discussed.