Comparison of "rollovers" and "switchers" among enrollees of Medicare HMOs.

Individuals who are able to enroll in an HMO and retain the physician-patient relationship they had developed under fee-for-service arrangements ("rollovers") may differ on average in health status and other characteristics from those who changed physicians to join an HMO ("switchers") and those who did not have a regular physician prior to joining. If such differences exist, they could have important implications for the relative performance of IPA-model HMOs, which tend to enroll significant numbers of rollovers, and staff model HMOs, which primarily enroll switchers and individuals without a regular physician. This study uses survey data on Medicare beneficiaries who enrolled in 17 HMOs under the Medicare competition demonstrations to compare rollovers to both switchers and enrollees who previously had no regular physician. The findings indicate that rollovers are very similar to each of the other categories of enrollees on demographic and socioeconomic characteristics as well as self-reported health status.