Medicare HMO Enrollment: Area Differences Affected by Factors Other Than Payment Rates

Pursuant to a congressional request, GAO reviewed the factors affecting Medicare risk health maintenance organization (HMO) enrollment, focusing on: (1) the patterns in HMO enrollment and Medicare payment rates; (2) selected geographical areas with higher enrollment, lower payment rates and areas with lower enrollment, higher payment rates; and (3) how the presence or absence of certain factors could affect enrollment.