TABLE 1.
Characteristics of physician organizations and their attributed Medicare beneficiaries
| All physician organizations | Matched sample of physician organizations | |||||
|---|---|---|---|---|---|---|
| Affiliated with health systems | Not affiliated with health systems | |||||
| N = 16 007 POs N = 19 770 556 beneficiaries | N = 1853 POs N = 2 855 419 beneficiaries | N = 1853 POs N = 2 091 563 beneficiaries | ||||
| Mean | SD | Mean | SD | Mean | SD | |
| Characteristics of Physician Organizations | ||||||
| Number of attributed beneficiaries | 1235 | 3616.5 | 1541 | 3012.8 | 1129 | 2817.8 |
| Number of physicians | ||||||
| Primary care | 10.0 | 42.7 | 13.4 | 26.3 | 10.0 | 87.4 |
| Specialty care | 9.0 | 54.0 | 11.5 | 41.2 | 8.7 | 63.1 |
| Total | 23.9 | 121.9 | 30.7 | 88.9 | 23.8 | 189.5 |
| Percentage of primary care physicians | 71.7 | 31.8 | 58.2 | 29.3 | 58.0 | 34.8 |
| Organization specialty, % | ||||||
| Primary care only | 59.6 | 34.1 | 48.9 | |||
| Primary and specialty care | 40.4 | 65.9 | 51.1 | |||
| Region, % | ||||||
| Northeast | 19.2 | 19.2 | 24.9 | |||
| Midwest | 25.4 | 25.4 | 22.1 | |||
| South | 38.7 | 38.1 | 37.6 | |||
| West | 16.7 | 17.2 | 15.4 | |||
| Characteristics of Medicare Beneficiaries | ||||||
| Age, mean | 70.1 | 5.9 | 69.6 | 5.8 | 69.5 | 6.0 |
| Female, % | 56.4 | 11.4 | 56.4 | 11.7 | 56.3 | 12.6 |
| Disabled, % | 29.3 | 19.2 | 31.6 | 17.6 | 31.5 | 20.3 |
| Dually eligible, % | 27.1 | 23.6 | 27.4 | 20.2 | 26.6 | 21.2 |
| Part D low‐income subsidy eligible, % | 2.8 | 3.5 | 3.1 | 4.5 | 3.1 | 4.5 |
| Mean HCC score | 1.2 | 0.4 | 1.2 | 0.4 | 1.2 | 0.4 |
| Race and ethnicity: White, % | 73.9 | 25.1 | 77.7 | 21.8 | 79.1 | 20.9 |
| Black | 10.7 | 15.7 | 10.6 | 15.7 | 10.2 | 15.8 |
| Hispanic | 8.5 | 15.7 | 5.7 | 10.2 | 5.1 | 9.3 |
| Asian/Pacific Islander | 3.4 | 9.1 | 2.1 | 6.6 | 1.8 | 4.9 |
| Neighborhood SES index, mean | 0.09 | 0.6 | 0.05 | 0.5 | 0.07 | 0.5 |
| Urbanization: Metropolitan area, % | 79.0 | 32.9 | 69.5 | 37.0 | 67.0 | 38.2 |
| Nonmetropolitan urban area | 14.0 | 28.9 | 20.7 | 32.8 | 21.3 | 32.2 |
| Nonmetropolitan rural area | 7.0 | 25.5 | 9.8 | 27.6 | 11.8 | 29.6 |
Matching variables included 13 PO‐level measures of aggregated beneficiary characteristics (mean age, percent female, percent disabled, percent dual eligible, percent low‐income subsidy eligible, percent with above‐median Hierarchical Condition Category score, mean neighborhood socioeconomic status index, percent living in metropolitan areas, percent living in nonmetropolitan urban areas, percent white, percent black, percent Hispanic, percent Asian/Pacific Islander) and three PO characteristics (number of attributed beneficiaries, total number of physicians, and percentage of physicians who provide primary care). Matching was conducted within hospital referral regions (defined as the plurality HRR for each PO based on beneficiary residence). HCC = Hierarchical Condition Category; SES = Socioeconomic Status. The median number of attributed beneficiaries per PO was 517 (affiliated POs) and 338 (nonaffiliated POs), and the median number of physicians per PO was 12 (affiliated POs) and 5 (nonaffiliated POs).