Table 1 Basic characteristics of the participants (n = 7510)
Variables | Knee pain | Clinical KOA | ||||
|---|---|---|---|---|---|---|
Yes (n = 3496) | No (n = 4014) | p-value | Yes (n = 640) | No (n = 6870) | p-value | |
Age (years, mean ± SD) | 63.1 ± 8.5 | 61.1 ± 8.6 | < 0.01* | 65.1 ± 8.6 | 61.9 ± 8.5 | < 0.01* |
BMI (kg/m2, mean ± SD) | 24.7 ± 3.6 | 23.8 ± 3.3 | < 0.01* | 25.3 ± 3.8 | 24.1 ± 3.4 | < 0.01* |
Times of pregnancy (mean ± SE) | 3.21 ± 0.02 | 3.00 ± 0.02 | < 0.01* | 3.33 ± 0.06 | 3.08 ± 0.01 | < 0.01* |
Abortion (%) | 2329(67.8) | 2652(67.8) | 0.95 | 413(65.8) | 4568(68.0) | 0.25 |
Oral contraceptives use (%) | 656(18.9) | 672(16.9) | 0.02* | 129(20.4) | 1199(17.6) | 0.08 |
Years of post-menopause (mean ± SD) | 13.8 ± 9.3 | 11.9 ± 9.2 | < 0.01* | 15.8 ± 9.5 | 12.5 ± 9.2 | < 0.01* |
History of HT (%) | 126(3.9) | 99(2.8) | 0.01* | 26(4.3) | 199(3.2) | 0.02* |
Education (%) |  |  | < 0.01* |  |  | 0.36 |
 Elementary or lower | 807(23.2) | 797(20.0) |  | 154(24.1) | 1450(21.2) |  |
 Junior high school | 1278(36.7) | 1424(35.7) |  | 229(35.8) | 2473(36.2) |  |
 High school | 1071(30.8) | 1379(34.5) |  | 199(31.1) | 2251(32.9) |  |
 College or higher | 325(9.3) | 393(9.8) |  | 57(8.9) | 661(9.7) |  |
Alcohol consumption (%) | Â | Â | 0.42 | Â | Â | 0.77 |
 Never | 3031(86.9) | 3513(87.7) |  | 557(87.2) | 5987(87.4) |  |
 Current | 410(11.8) | 433(10.8) |  | 71(11.1) | 772(11.2) |  |
 Former | 47(1.3) | 58(1.5) |  | 11(1.7) | 94(1.4) |  |
Physical exercise (%) | 3096(88.6) | 3605(89.8) | 0.07 | 577(90.1) | 6124(89.2) | 0.43 |
Work posture (%) | Â | Â | 0.22 | Â | Â | 0.29 |
 Sitting | 1031(29.6) | 1268(31.7) |  | 207(32.5) | 2092(30.6) |  |
 Standing | 1765(50.7) | 1942(48.6) |  | 320(50.2) | 3387(49.5) |  |
 Bending | 535(15.4) | 616(15.4) |  | 90(14.1) | 1061(15.5) |  |
 Squatting or kneeling | 150(4.3) | 173(4.3) |  | 20(3.1) | 303(4.4) |  |
Shift work | 1495(42.8) | 1522(37.9) | < 0.01* | 264(41.2) | 2753(40.1) | 0.56 |