We use a matched comparison group design for the study. New enrollees in PACE (treatment group) during 2006-2008 in each of those eight states were either matched to: (1) new enrollees in the HCBS 1915(c) waiver programs and new NH entrants in each of those three years; or (2) new enrollees in HCBS waiver programs alone. Participants in HCBS waiver programs alone could offer a reasonable comparison group for PACE enrollees, since waiver participants also have to meet standards for NH certifiability in their respective states, just like their counterparts in PACE. However, the National PACE Association and the PACE plans have previously asserted that PACE enrollees have higher health care service and support requirements than HCBS enrollees. For instance, some PACE enrollees likely would have entered a NH had PACE not been a local alternative. To address such concerns about unmeasured differences between PACE and matched comparison group enrollees in our analysis, we include in the pool of potential comparison group members both new HCBS waiver enrollees and new NH entrants in constructing the first matched comparison group, thereby offering a credible alternative to a comparison group comprised of HCBS waiver enrollees alone. This approach allows the matching algorithm (described below) to choose the closest matches from the comparison group pool for each PACE enrollee, regardless of whether the closest match for the enrollee is a NH entrant or waiver enrollee.9
For each of the eight states, the treatment group is comprised of new enrollees in PACE who meet the following sample selection criteria: (1) entered PACE between July 2006 and December 2008; (2) were enrolled in FFS Medicare for at least one month in the year prior to enrollment in PACE, had nonmissing information on Medicare service utilization in the prior year, and were at least 66 years old at PACE entry; (3) were enrolled in Medicaid within a month of entering PACE; and (4) had at least one month of enrollment during the followup period, that is, was alive and enrolled in PACE for at least one month (to ensure nonzero Medicare/Medicaid capitation payments). HCBS waiver enrollees and NH entrants in the comparison group had to meet similar criteria, as follows: (1) entered a type G or type H waiver program between July 2006 and December 2008, or entered a NH over the same period with the duration of the first stay being at least 21 days;10 (2) were enrolled in FFS Medicare in the year prior to enrollment in HCBS or NH entry, had nonmissing information on Medicare service utilization in the prior year, and were at least 66 years old at HCBS/NH entry; (3) had a ZIP code of residence that was among the ZIP codes of residence for PACE enrollees in that state and for the same year of sample entry; and (4) had at least one month of Medicare and Medicaid FFS enrollment during the followup period, that is, was alive and not in managed care for at least one month (we examine FFS Medicare/Medicaid expenditures only for our comparison group members; that is, we do not examine managed care expenditures for comparison group members (we stop following comparison group members once they enroll in either Medicare or Medicaid managed care). Also, we do not examine post-disenrollment FFS expenditures for PACE enrollees who disenroll from the program and return to FFS). Figure 1a, Figure 1b and Figure 1c describe the sample selection process for PACE entrants as well as sample members in the comparison group (HCBS waiver enrollees and NH entrants).