Table 1.
Background Characteristics of the Study Samples
| Calibration Sample (N = 520) | Validation Sample (N = 102) | Test–Retest Sample (N = 57) | |
| Age range, y | 60–101 | 59–98 | 62–98 |
| Mean age, y (SD) | 76.19 (9.08) | 78.22 (9.35) | 77.82 (8.06) |
| Female, # (%) | 389 (74.8) | 83 (81.4) | 50 (87.7) |
| Ethnicity, # (%) N = 513 | |||
| Hispanic or Latino | 6 (1.2) | 4 (4.0) | 3 (5.3) |
| Race # (%) N = 517 | |||
| Asian | 13 (2.5) | 2 (2.0) | 1 (1.8) |
| Other | 10 (1.9) | 5 (4.9) | 3 (5.3) |
| African American | 79 (15.3) | 21 (20.6) | 14 (24.6) |
| White | 411 (79.5) | 73 (71.6) | 39 (68.4) |
| American Indian or Alaskan native | 4 (0.8) | 1 (0.9) | |
| Education, # (%) N = 512 | |||
| Post-graduate | 99 (19.3) | 16 (15.7) | 8 (14) |
| College graduate | 105 (20.5) | 17 (16.7) | 5 (8.8) |
| Some college | 138 (27.0) | 27 (26.5) | 15 (26.3) |
| High school graduate | 109 (21.3) | 19 (18.6) | 18 (31.6) |
| Less than high school | 61 (11.9) | 23 (22.5) | 11 (19.3) |
| Health level, # (%) N = 512 | |||
| Excellent | 48 (9.4) | ||
| Good | 200 (39.1) | ||
| Fair | 110 (21.5) | ||
| Poor | 35 (6.8) | ||
| Very poor | 119 (23.2) | ||
| SF-36 Physical Function Score (22) | |||
| Mean (SD) | 21.4 (5.2) | 19.9 (5.5) | |
| Min, max | 10, 29 | 10, 29 | |
| 10–20 | 43.05 (223) | 55.88 (57) | |
| 21–29 | 56.95 (295) | 44.12 (45) | |
| Walking aids, # (%) N = 511 | |||
| Do not use walking aid/wheelchair | 329 (64.4) | 55 (53.9) | 29 (50.9) |
| Use walking aid only | 131 (25.6) | 37 (36.3) | 21 (36.8) |
| Use both walking aid and wheelchair | 42 (8.2) | 7 (6.9) | 5 (8.8) |
| Use wheelchair and never walk | 9 (1.8) | 3 (2.9) | 2 (3.5) |