Table 1.
Subject level characteristics stratified by the more painful limb.
| Patellofemoral Pain (n = 404) | Tibiofemoral Pain (n =1248) | Combined Pain (n = 300) | p-valuea | |
|---|---|---|---|---|
| Age, median, IQR | 61.5 (55.0, 69.0) | 62.00 (55.0, 70.0) | 61.00 (55.0, 69.0) | 0.87 |
| Female, n (%) | 231 (57.2) | 685 (54.9) | 186 (62.0) | 0.08 |
| Race, n (%) | <0.001 | |||
| White or Caucasian | 319 (79.0) | 1052 (84.3) | 229 (76.3) | |
| African American | 70 (17.3) | 175 (14.0) | 66 (22.0) | |
| Others | 15 (3.7) | 21 (1.7) | 5 (1.7) | |
| BMI, n (%) | 0.14 | |||
| BMI < 25 | 101 (25.0) | 279 (22.3) | 61 (20.3) | |
| 25 ≤ BMI < 30 | 139 (34.4) | 499 (40.0) | 109 (36.3) | |
| 30 ≤ BMI | 164 (40.6) | 470 (37.7) | 130 (43.3) | |
| Radiographic Tibiofemoral Joint Disease severity, n (%) | ||||
| Grade 0 | 68 (16.8) | 179 (14.3) | 43 (14.3) | 0.003 |
| Grade 1 | 155 (38.4) | 418 (33.5) | 101 (33.7) | |
| Grade 2 | 79 (19.6) | 194 (15.5) | 47 (15.7) | |
| Grade 3 | 78 (19.3) | 299 (24.0) | 78 (26.0) | |
| Grade 4 | 24 (5.9) | 158 (12.7) | 31 (10.3) | |
| Clinical Center, n (%)b | <0.0001 | |||
| A | 60 (14.9) | 159 (12.7) | 61 (20.3) | |
| B | 42 (10.4) | 259 (20.8) | 30 (10.0) | |
| C | 163 (40.3) | 371 (29.7) | 129 (43.0) | |
| D | 92 (22.8) | 390 (31.3) | 66 (22.0) | |
| E | 47 (11.6) | 69 (5.5) | 14 (4.7) | |
a
For continuous variables, Kruskal-Wallis test is used. For categorical variable, Chi-squared test is used.
b
Blinded clinical site indicators as they appear in the publically available Osteoarthritis Initiative (OAI) database.
BMI = body mass index; IQR = interquartile range