Table 1. Hospital, Patient, and Market Characteristics by Hospital Participation in Bundled Payment Program, 2011-2017.
| Hospitals participating in bundled payment program | Hospitals not participating in bundled payment program | P value | ||
|---|---|---|---|---|
| Voluntary | Mandatory | |||
| Hospital characteristics | ||||
| No. of hospitals | 92 | 752 | 894 | |
| Total No. of hospital beds, mean (SD) | 367 (321) | 279 (250) | 255 (228) | <.001 |
| Profit status, No. (%) | ||||
| Nonprofit | 71 (78.0) | 458 (62.1) | 551 (63.3) | .002 |
| For profit | 19 (20.9) | 186 (25.2) | 238 (27.4) | |
| Government | 1 (1.1) | 93 (12.6) | 81 (9.3) | |
| Hospital status, No. (%) | ||||
| Major teaching | 16 (17.6) | 76 (10.3) | 92 (10.6) | .004 |
| Minor teaching | 54 (59.3) | 349 (47.4) | 400 (46.0) | |
| Nonteaching | 21 (23.1) | 312 (42.3) | 378 (43.5) | |
| Safety net hospitals, No. (%) | 19 (20.7) | 230 (30.6) | 192 (21.5) | <.001 |
| Joint replacement complication rate, mean (SD)a | 2.77 (0.58) | 2.78 (0.55) | 2.75 (0.54) | .57 |
| Risk-adjusted readmission rate, mean (SD)a | 4.57 (0.60) | 4.62 (0.56) | 4.61 (0.59) | .76 |
| Patient characteristics | ||||
| No. of episodes | 147 052 | 576 505 | 829 838 | |
| No. of patients | 128 438 | 500 253 | 718 065 | |
| Age at admission, mean (SD), y | 73.5 (7.5) | 73.2 (7.8) | 73.1 (7.7) | <.001 |
| Sex, No. (%) | ||||
| Female | 52 322 (35.6) | 208 440 (36.2) | 303 369 (36.6) | <.001 |
| Male | 94 730 (64.4) | 368 065 (63.8) | 526 469 (63.4) | |
| Race and ethnicity, No. (%)b | ||||
| White | 128 674 (87.5) | 513 480 (89.1) | 751 220 (90.5) | <.001 |
| Black | 11 101 (7.6) | 35 194 (6.1) | 47 763 (5.8) | |
| Otherc | 7277 (5.0) | 27 831 (4.8) | 30 855 (3.7) | |
| Medicare and Medicaid dual eligibility, No. (%) | 12 185 (8.3) | 60 815 (10.6) | 76 641 (9.2) | <.001 |
| Market characteristics | ||||
| Medicare Advantage, median (IQR), %d | 0.31 (0.27-0.42) | 0.32 (0.25-0.45) | 0.30 (0.21-0.40) | <.001 |
| Accountable care organizations, median (IQR), %e | 0.1 (0-0.2) | 0.02 (0-0.2) | 0.02 (0-0.2) | <.001 |
| Hospital Herfindahl-Hirschman Index, median (IQR)f | 761 (394-1571) | 1060 (629-3193) | 2151 (633-3513) | <.001 |
Abbreviation: IQR, interquartile range.
Obtained directly as rates from Hospital Compare.
Obtained from Medicare claims, which contained White and Black categories that were used directly in the analysis. Information about race was assessed due to the potential relationship between patient race and both receipt of joint replacement in the bundled payment program and spending on institutional care.
This category included Asian, Hispanic, North American Native, and other.
Defined based on the proportion of all Medicare beneficiaries enrolled.
Defined as the proportion of all Medicare fee-for-service beneficiaries enrolled.
Measure of market concentration in which higher values represent more concentration (lower competition) and lower values represent less concentration (greater competition). In this study, this index represents the concentration of hospitals in a given market.