Table 1 Characteristics of the participants with knee pain
From: Disability due to knee pain and somatising tendency in Japanese adults
|  | All (n = 14,695) | Knee pain without difficulty in ADL (n = 12,161) | Knee pain with difficultly but without sick leave (n = 1954) | Knee pain with sick leave (n = 580) | p-value* |
|---|---|---|---|---|---|
Age (%) |  |  |  |  | < 0.001 |
 20–29 | 1942 (13.2) | 1569 (12.9) | 271 (13.9) | 102 (17.6) |  |
 30–39 | 2903 (19.8) | 2345 (19.3) | 411 (21.0) | 147 (25.3) |  |
 40–49 | 3462 (23.6) | 2875 (23.6) | 441 (22.6) | 146 (25.2) |  |
 50–59 | 4322 (29.4) | 3599 (29.6) | 588 (30.1) | 135 (23.3) |  |
 60–64 | 2066 (14.1) | 1773 (14.6) | 243 (12.4) | 50 (8.6) |  |
Sex (%) | Â | Â | Â | Â | 0.0003 |
 Men | 7421 (50.5) | 6082 (50.0) | 1000 (51.2) | 339 (58.5) |  |
 Women | 7274 (49.5) | 6079 (50.0) | 954 (48.8) | 241 (41.6) |  |
BMI (%) | Â | Â | Â | Â | 0.0003 |
 < 25 | 11,078 (75.4) | 9228 (75.9) | 1431 (73.2) | 419 (72.2) |  |
 25–29 | 2811 (19.1) | 2311 (19.0) | 381 (19.5) | 119 (20.5) |  |
 ≥ 30 | 806 (5.5) | 622 (5.1) | 142 (7.3) | 42 (7.2) |  |
Marital status (%) |  |  |  |  | < 0.001 |
 Not married | 6249 (42.5) | 5069 (41.7) | 884 (45.2) | 296 (51) |  |
 Married | 8446 (57.5) | 7092 (58.3) | 1070 (54.8) | 284 (49) |  |
Education (%) | Â | Â | Â | Â | 0.003 |
 No college | 7820 (53.2) | 6402 (52.6) | 1077 (55.1) | 341 (58.8) |  |
 Some college | 6875 (46.8) | 5759 (47.4) | 877 (44.9) | 239 (41.2) |  |
Exercise (%) | Â | Â | Â | Â | 0.016 |
 No regular exercise | 11,585 (78.8) | 9577 (78.8) | 1524 (78) | 484 (83.5) |  |
 Regular exercise | 3110 (21.2) | 2584 (21.3) | 430 (22) | 96 (16.6) |  |
PHQ-2 (%)a |  |  |  |  | < 0.001 |
 0 | 9415 (64.1) | 8028 (66.0) | 1060 (54.3) | 327 (56.4) |  |
 1 | 2546 (17.3) | 2054 (16.9) | 399 (20.4) | 93 (16.0) |  |
 2 | 2734 (18.6) | 2079 (17.1) | 495 (25.3) | 160 (27.6) |  |
Chronic knee pain (%) |  |  |  |  | < 0.001 |
 No | 4906 (33.4) | 4096 (33.7) | 509 (26.1) | 301 (51.9) |  |
 Yes | 9789 (66.6) | 8065 (66.3) | 1445 (74.0) | 279 (48.1) |  |
Osteoarthritis (%) | 607 (4.1) | 328 (2.7) | 209 (10.7) | 70 (12.1) | < 0.001 |
Rheumatoid arthritis (%) | 229 (1.6) | 138 (1.1) | 67 (3.4) | 24 (4.1) | < 0.001 |
Fibromyalgia (%) | 81 (0.6) | 38 (0.3) | 27 (1.4) | 16 (2.8) | < 0.001 |
SSS-8 (%) |  |  |  |  | < 0.001 |
 No to minimal | 5262 (35.8) | 4679 (38.5) | 418 (21.4) | 165 (28.5) |  |
 Low | 4175 (28.4) | 3542 (29.1) | 526 (26.9) | 107 (18.5) |  |
 Medium | 2510 (17.1) | 2069 (17.0) | 363 (18.6) | 78 (13.5) |  |
 High | 1434 (9.8) | 1079 (8.9) | 284 (14.5) | 71 (12.2) |  |
 Very high | 1314 (8.9) | 792 (6.5) | 363 (18.6) | 159 (27.4) |  |