Table 2.
Outcomes during Phase II and Comparison to Phase I Outcomes
| Outcome | Phase II Outcomes | Phase I Outcomesb (n = 322) | Difference in Outcomes for Phase II (Primary Sample) and Phase Ic | ||
|---|---|---|---|---|---|
| Primary Sample–Beneficiaries Enrolled During Phase II (n = 483) | Secondary Sample–Beneficiaries Enrolled During Phase II and Phase I High‐risk Enrollees Who Remained Enrolled During Phase II (n = 736) | Primary Sample After Weightinga (n = 483) | |||
| Annualized hospitalizations, number per person per year | |||||
| Control group mean | 0.743 | 0.723 | 0.524 | 0.872 | −0.129 |
| Regression‐adjusted treatment–control difference (90% confidence interval) | 0.065 (−0.086, 0.216) | 0.039 (−0.080, 0.157) | 0.106 (−0.025, 0.237) | −0.293*** (−0.458, −0.129) | 0.359*** (0.136, 0.581) |
| Annualized outpatient emergency department visits, number per person per year | |||||
| Control group mean | 0.747 | 0.729 | 0.655 | NA | NA |
| Regression‐adjusted treatment–control difference (90% confidence interval) | 0.010 (−0.135, 0.156) | −0.059 (−0.174, 0.056) | −0.017 (−0.145, 0.111) | NA | NA |
| Medicare Part A and B expenditures, dollars per beneficiary per month | |||||
| Without program fees | |||||
| Control group mean | 1,748 | 1,694 | 1,284 | 1,415 | 333 |
| Regression‐adjusted treatment–control difference (90% confidence interval) | 16 (−315, 347) | 29 (−218, 277) | 118 (−151, 386) | −425** (−698, −152) | 441* (13, 689) |
| With program fees | |||||
| Regression‐adjusted treatment–control difference (90% confidence interval) | 276 (−55, 607) | 264* (17, 512) | 380** (112, 648) | −313* (−587, −40) | 589** (161, 1,017) |
| Mean program fees paid for beneficiaries in treatment group, dollars per beneficiary per month | $260 | $235 | $262 | $112 | $148 |
| Died within 2 years of enrollmentd, % | |||||
| Control group mean, % | 15.5 | NA | NA | 13.8 | 1.7 |
| Regression‐adjusted odds ratio (90% confidence interval) | 0.88 (0.49–1.59) | NA | NA | 0.33 (0.13–0.81)** | 0.55e |
| Mean number of follow‐up months (treatment and control) | 25.5 | 30.8 | 24.5 | 49.4 | −23.9 |
Sample sizes are treatment and control groups combined. The control group mean is weighted but not regression‐adjusted.
*p < .10, **p < .05, ***p < .01.
The Phase II enrollees are weighted to resemble the Phase I enrollees on baseline characteristics.
The results from Phase I come from Burwell (2014), who used high‐risk enrollees through June 2009. The sample size (n = 322) differs from the sample size in Table 1 (n = 366), which includes beneficiaries who enrolled through March 2010.
The p‐values are for tests of the null hypothesis that the impact estimates in the two phases are the same.
The sample is limited to beneficiaries who enrolled early enough to be followed up for 2 years before the end of the period (n = 369 for the primary sample for Phase II and n = 248 for Phase I).
p = .13 for the test that the odds ratios in the two phases are the same.
NA, not available.