Table 1 Characteristics of the study population from the survey with and without chronic knee pain
Variable | Without chronic knee pain n (%) | Chronic knee pain n (%) | P-value |
|---|---|---|---|
Total | 6344 (79.2) | 1664 (20.8) | Â |
Age (y) | 61.3 ± 8.7 | 65.2 ± 9.3 | <.0001 |
Age, n (%) | |||
 50–59 | 2583 (85.8) | 428 (14.2) | <.0001 |
 60–69 | 2098 (79.4) | 543 (20.6) |  |
 70–79 | 1373 (71.8) | 539 (28.2) |  |
  ≥ 80 | 290 (65.3) | 154 (34.7) |  |
Sex, n (%) | |||
 Men | 3024 (88) | 411 (12) | <.0001 |
 Women | 3320 (72.6) | 1253 (27.4) |  |
BMI (kg/m2) | 24.0 ± 3.1 | 24.7 ± 3.3 | <.0001 |
BMI (categorical), n (%)a | |||
 Underweight (< 18.5) | 171 (83.0) | 35 (17.0) | <.0001 |
 Normal (18.5–24.9) | 3984 (81.2) | 922 (18.8) |  |
 Overweight (25.0–29.9) | 1968 (76.6) | 601 (23.4) |  |
 Obesity (≥30) | 221 (67.6) | 106 (32.4) |  |
Smoking status, n (%) | |||
 No | 5308 (78.4) | 1464 (21.6) | <.0001 |
 Yes | 965 (85.1) | 169 (14.9) |  |
Alcohol consumption, n (%) | |||
 None | 2333 (74.8) | 787 (25.2) | <.0001 |
  ≤ 1 drink/mo | 1037 (77.9) | 295 (22.2) |  |
 2 drinks/mo to 3 drinks/wk | 1576 (83.2) | 319 (16.8) |  |
  ≥ 4 drinks/wk | 1334 (85) | 236 (15) |  |
Occupation, n (%) | |||
 Unemployed (student, housewife, etc.) | 2974 (74.7) | 1006 (25.3) | <.0001 |
 Office work | 701 (92.1) | 60 (7.9) |  |
 Sales and services | 720 (85.2) | 125 (14.8) |  |
 Agriculture, forestry, and fishery | 505 (75.3) | 166 (24.7) |  |
 Machine fitting and simple labor | 1430 (82.6) | 302 (17.4) |  |
Household income, n (%) b | |||
 Low | 1608 (69.1) | 719 (30.9) | <.0001 |
 Mid-low | 1702 (79.8) | 431 (20.2) |  |
 Mid-high | 1441 (83.3) | 289 (16.7) |  |
 High | 1566 (87.9) | 216 (12.1) |  |
Education, n (%) | |||
 ≤ 6 y | 2326 (68.8) | 1057 (31.2) | <.0001 |
 7–9 y | 1127 (80.9) | 266 (19.1) |  |
 10–12 y | 1792 (87.5) | 256 (12.5) |  |
 ≥ 13 y | 1086 (93.2) | 79 (6.8) |  |
Duration of sleep (h), mean ± sd | 6.6 ± 1.4 | 6.4 ± 1.7 | <.0001 |
Depressive symptom, n (%) c | 307 (64.6) | 168 (35.4) | <.0001 |
Physical activity, n(%) | |||
 Low | 4083 (77.4) | 1195 (22.6) | <.0001 |
 High | 2261 (82.8) | 469 (17.2) |  |
Sedentary behaviors (h), mean ± sd | 6.5 ± 3.6 | 6.9 ± 3.8 | 0.0145 |
Sedentary behaviors (h) d | |||
 < 5 | 2123 (33.5) | 492 (29.6) | 0.0909 |
 5–7 | 1950 (30.7) | 498 (29.9) |  |
 8–10 | 1474 (23.2) | 415 (24.9) |  |
 > 10 | 797 (12.6) | 259 (15.6) |  |