When medical group and HMO part company: disenrollment decisions in Medicare HMOs.

Medicare beneficiaries who enroll in “risk contract” Health Maintenance Organizations (HMOs) are covered for services only if they are provided or approved by the HMO. Thus, their enrollment decisions involve selecting a health care delivery system and may be influenced by whether the HMO has contracts with particular providers. Disenrollment decisions, in turn, may be influenced by breaks in contracts between the HMO and its medical groups. This study examines decisions made by Medicare HMO enrollees when their HMO terminated its relationship with a major medical group; the group then signed a contract with a competing HMO. Beneficiaries were forced to choose between remaining with their HMO and switching to another provider, and switching to the competing HMO where they could keep their provider. Beneficiaries demonstrated considerable loyalty to their providers; nearly 60% switched to the competing HMO. Previous research on health care coverage decisions has been based on models which did not address consumers' knowledge, options, and information sources. In this decision context, we found that knowledge and information sources were the most important determinants of beneficiary decisions.