| 65YRF | Women 65-69 years of age (in the first base year) who were not receiving welfare and whose original reason for Medicare entitlement was becoming 65 years old (rather than a disability identified at an earlier age). |
| NOCOST | A subset of those in group 65YRF defined by having no Medicare reimbursement in the prior year. |
| CVD/CA | Anyone hospitalized in the prior year for cerebrovascular disease and/or cancer (Eighth Revision International Classification of Diseases codes 140- 201 or 430-438). |
| 2HOSPS | Anyone with at least two hospitalizations in the prior year. |