| Practice location | Site 1 | Site 2 | Site 3 | Site 4 | Site 5 | Site 6 |
| Urban | Urban | Urban | Urban | Urban | Rural | |
| No. of patients visits per year | 60 500 | 24 700 | 13 800 | 13 000 | 4500 | 5000 |
| Patients aged 65 years or above (%) | 35 | 20 | 15 | 13 | 99.5 | 30 |
| Race | ||||||
| African–American (%) | 8 | 5 | 75 | 98 | 19 | 1 |
| Caucasian (%) | 79 | 29 | 14 | 1 | 79 | 98 |
| Other (%) | 13 | 66 | 11 | 1 | 2 | 1 |
| Payor | ||||||
| Medicare (%) | 25 | 20 | 11 | 22 | 2 | 8 |
| Medicaid (%) | 5 | 10 | 3 | 49 | 4 | 1 |
| Commercial (including managed care) (%) | 65 | 65 | 84 | 29 | 94 | 90 |
| Self-pay (%) | 5 | 5 | 2 | <1 | 0 | 1 |
Two research assistants conducted manual retrospective chart screening, covering the 12-month period from 1 January to 31 December 2005.