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Table 2 Prevalence of knee OA according to different definitions

From: Health-related quality of life in relation to symptomatic and radiographic definitions of knee osteoarthritis: data from Osteoarthritis Initiative (OAI) 4-year follow-up study

Variable Baseline N (%) All observations N (%)
N 4278 14,161
Symptomatic OA statusa (2-scale)
 No 3134 (73.8) 9538 (67.8)
 Yes, uni- or bilateral 1114 (26.2) 4536 (32.2)
Symptomatic OA statusa (3-scale)
 No 3134 (73.8) 9538 (67.8)
 Yes, unilateral 762 (17.9) 2999 (21.3)
 Yes, bilateral 352 (8.3) 1537 (10.9)
K-L grade ≥ 2 (2-scale)
 No 1860 (43.5) 3395 (24.0)
 Yes, uni- or bilateral 2418 (56.5) 10,766 (76.0)
K-L grade ≥ 2 (3-scale)
 No 1860 (43.5) 3395 (24.0)
 Yes, unilateral 1112 (26.0) 4785 (33.8)
 Yes, bilateral 1306 (30.5) 5981 (42.2)
The highest K-L grade
 0 1199 (28.0) 2051 (14.5)
 1 661 (15.5) 1344 (9.5)
 2 1288 (30.1) 5544 (39.1)
 3 841 (19.7) 3693 (26.1)
 4 289 (6.8) 1529 (10.8)
Mean of K-L grades
 0.0 1199 (28.0) 2051 (14.5)
 0.5 383 (9.0) 774 (5.5)
 1.0 612 (14.3) 2032 (14.3)
 1.5 550 (12.9) 2346 (16.6)
 2.0 728 (17.0) 3151 (22.3)
 2.5 391 (9.1) 1660 (11.7)
 3.0 313 (7.3) 1470 (10.4)
 3.5 100 (2.3) 566 (4.0)
 4.0 2 (0.0) 111 (0.8)
Combination of K-L grades
 (0;0) 1199 (28.0) 2051 (14.5)
 (1;0) 383 (9.0) 774 (5.5)
 (1;1) 278 (6.5) 570 (4.0)
 (2;0) 334 (7.8) 1462 (10.3)
 (2;1) 403 (9.4) 1714 (12.1)
 (2;2) 551 (12.9) 2368 (16.7)
 (3;0) 147 (3.4) 632 (4.5)
 (3;1) 123 (2.9) 525 (3.7)
 (3;2) 340 (7.9) 1466 (10.4)
 (3;3) 231 (5.4) 1070 (7.6)
 (4;0) 54 (1.3) 258 (1.8)
 (4;1) 51 (1.2) 194 (1.4)
 (4;2) 82 (1.9) 400 (2.8)
 (4;3) 100 (2.3) 566 (4.0)
 (4;4) 2 (0.0) 111 (0.8)
  1. aK-L grade ≥ 2 and knee pain on more than half the days during past month in the same knee