| Multiple sites | 168 (22.1) |
| Others | 53 (7.0) |
| Unknown | 278 (36.8) |
| US geographic region, n (%) |
|
| South | 468 (61.9) |
| West | 166 (22.0) |
| Midwest | 77 (10.2) |
| Northeast | 45 (6.0) |
| Payer type, n (%) |
|
| Medicare | 296 (39.2) |
| PPO/commercial | 234 (30.9) |
| HMO/managed care | 87 (11.5) |
| Medicaid | 58 (7.7) |
| Other | 60 (7.9) |
| Unknown | 21 (2.8) |