Table 4. Mean Outcomes and Adjusted Difference-in-Differences Estimates for Hospitalizations, Emergency Department Visits, and Medicare Spending for All Medicare Patients and High-Risk Medicare Patients.
| Patients | Intervention Group | Comparison Group | Adjusted Difference-in-Differences (90% CI)a | P Value |
|---|---|---|---|---|
| All Medicare FFS Patients | ||||
| Medicare patients per quarter, mean No. | 34 364 | 68 854 | NA | NA |
| Hospitalizations, rate per 1000 patients per quarter | ||||
| All-cause | ||||
| Preintervention year | 79.4 | 78.6 | NA | NA |
| Intervention mo | ||||
| 1-12 | 75.4 | 71.9 | 1.4 (−2.4 to 5.3) | .54 |
| 13-30 | 71.5 | 68.9 | 1.4 (−2.1 to 5.0) | .51 |
| Ambulatory care-sensitive | ||||
| Preintervention year | 13.0 | 12.8 | NA | NA |
| Intervention mo | ||||
| 1-12 | 11.5 | 11.3 | −0.1 (−1.4 to 1.2) | .89 |
| 13-24b | 11.6 | 11.0 | 0.4 (−0.9 to 1.7) | .61 |
| Outpatient ED visits, rate per 1000 patients/quarter | ||||
| Preintervention year | 79.2 | 80.8 | NA | NA |
| Intervention mo | ||||
| 1-12 | 81.2 | 80.6 | 2.2 (−1.5 to 6.0) | .33 |
| 13-30 | 83.0 | 87.8 | −2.5 (−6.2 to 1.1) | .26 |
| Medicare Part A and B spending, $/patient/per mo | ||||
| Preintervention year | 989 | 976 | NA | NA |
| Intervention mo | ||||
| 1-12 | 987 | 949 | 12 (−27 to 52) | .61 |
| 13-30 | 1006 | 987 | −1 (−40 to 39) | .98 |
| High-Risk Medicare FFS Patients | ||||
| Medicare patients per quarter, mean No. | 10 036 | 20 839 | NA | NA |
| Hospitalizations, rate per 1000 patients/quarter | ||||
| All-cause | ||||
| Preintervention year | 162.3 | 158.0 | NA | NA |
| Intervention mo | ||||
| 1-12 | 149.2 | 140.7 | 2.8 (−7.1 to 12.7) | .64 |
| 13-30 | 142.0 | 137.2 | 0.2 (−9.4 to 9.7) | .98 |
| Ambulatory care-sensitive | ||||
| Preintervention year | 31.8 | 31.1 | NA | NA |
| Intervention mo | ||||
| 1-12 | 27.9 | 26.7 | 0.6 (−3.1 to 4.2) | .80 |
| 13-24b | 28.7 | 27.5 | 0.9 (−2.9 to 4.7) | .92 |
| Outpatient ED visits, rate per 1000 patients/quarter | ||||
| Preintervention year | 133.7 | 137.5 | NA | NA |
| Intervention mo | ||||
| 1-12 | 133.8 | 129.9 | 8.3 (−0.9 to 17.5) | .14 |
| 13-30 | 137.7 | 147.9 | −4.6 (−14.4 to 5.1) | .44 |
| Medicare Part A and B spending, $/patient/mo | ||||
| Preintervention year | 1851 | 1822 | NA | NA |
| Intervention mo | ||||
| 1-12 | 1789 | 1728 | 10 (−89 to 110) | .87 |
| 13-30 | 1808 | 1773 | −11 (−115 to 92) | .86 |
Abbreviations: ED, emergency department; FFS, fee-for-service; NA, not applicable.
a
The regressions adjusted for the same variables indicated in Table 3.
b
To ensure comparability of measure definition throughout the study period, we did not construct rates of ambulatory care-sensitive conditions after October 2015, when Medicare claims began using the 10th edition (instead of the 9th) revision of International Classification of Diseases (ICD). The other outcomes do not rely on ICD codes and so could be constructed through the end of the program.