Table 3. Marginal Effects Holding Covariates at Subpopulation Means for ACOs With a High and Low Proportion of Beneficiaries of Racial and Ethnic Minority Groups.
| Characteristic | Marginal effects for low-proportion ACOsa | Marginal effects for high-proportion ACOsa | P value for interaction |
|---|---|---|---|
| Members of racial and ethnic minority groups, % (per 10 percentage points) | 0.04 (– 1.80 to 1.87) | 0.12 (– 5.96 to 6.20) | NA |
| Earned shared savings year prior | – 9.78 (– 19.26 to – 0.20) | – 32.28 (– 49.08 to – 15.4) | .19 |
| Beneficiary characteristics | |||
| With disabilities | 0.54 (– 0.01 to 1.09) | 1.79 (0.55 to 3.02) | .84 |
| Dual Medicaid eligible, % | – 0.05 (– 0.31 to 0.20) | – 0.18 (– 1.01 to 0.65) | .02 |
| Percentile of average HCC risk score for aged non–dual-eligible beneficiaries | 0.12 (0 to 0.23) | 0.38 (0.14 to 0.63) | .07 |
| Organizational characteristics | |||
| Cohort | |||
| 2012 | 1 [Reference] | 1 [Reference] | NA |
| 2013 | 15.03 (– 3.42 to 33.47) | 16.02 (– 3.65 to 35.69) | .69 |
| 2014 | – 10.62 (– 25.77 to 4.53) | – 13.4 (– 31.33 to 4.53) | .79 |
| 2015 | – 5.12 (– 22.49 to 12.25) | – 6.22 (– 26.95 to 14.52) | .18 |
| 2016 | – 21.91 (– 38.2 to – 5.6) | – 30.06 (– 47.41 to – 12.7) | .69 |
| 2017 | – 24.19 (– 40.88 to – 7.5) | – 33.79 (– 50.97 to – 16.6) | .25 |
| No. of beneficiaries (100s) | 0.07 (– 0.05 to 0.18) | 0.22 (– 0.1 to 0.55) | .58 |
| Organizing entity | |||
| Physician led | 1 [Reference] | 1 [Reference] | NA |
| Hospital led | – 1.06 (– 5.54 to 3.43) | – 3.67 (– 19.04 to 11.7) | .49 |
| Both | – 0.47 (– 5.72 to 4.78) | – 1.59 (– 19.35 to 16.18) | .32 |
| Risk model | |||
| Always upside | 1 [Reference] | 1 [Reference] | NA |
| Ever downside risk | – 2.92 (– 9.48 to 3.65) | – 9.63 (– 29.9 to 10.65) | .55 |
| No. of clinicians (100s) | – 0.38 (– 0.80 to 0.04) | – 1.24 (– 2.26 to – 0.20) | .07 |
| Primary care clinicians, % | 0.18 (– 0.01 to 0.37) | 0.6 (0.13 to 1.08) | .89 |
| Advanced practice clinicians, % | – 0.9 (– 1.62 to – 0.10) | – 2.98 (– 3.69 to – 2.20) | .55 |
| Out-of-network care, % | 0.06 (– 0.08 to 0.2) | 0.21 (– 0.24 to 0.66) | .44 |
| Community characteristics | |||
| Geography | |||
| Suburban | 1 [Reference] | 1 [Reference] | NA |
| Urban | – 3.91 (– 8.70 to 0.89) | – 12.9 (– 29.60 to 3.80) | .30 |
| Percentage dual Medicaid/Medicare eligible | – 1.02 (– 2.67 to 0.62) | – 3.38 (– 8.38 to 1.62) | .01 |
| Income level less than the poverty line, % | – 0.66 (– 1.58 to 0.26) | – 2.18 (– 4.67 to 0.31) | .89 |
| No. of PCPs per 1000 residents | 4.46 (– 1.68 to 10.60) | 14.73 (– 2.03 to 31.48) | .84 |
| County median income (1000s USD) | – 0.27(– 0.58 to 0.04) | – 0.89 (– 1.61 to −0.17) | .27 |
Abbreviations: ACO, accountable care organization; NA, not applicable; PCP, primary care physician.
a
Marginal effects calculated from fully adjusted model holding all covariates at their subpopulations means and modes. The ACOs in the highest quartile of proportion of beneficaries of racial and ethnic minority groups were designated high-proportion ACOs, and ACOs in the lowest 3 quartiles were designated low-proportion ACOs.