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Table 1 Baseline characteristics and outcomes of the study cohort summarized by their count and fraction (N (%)) for categorical or the mean and standard deviation for continuous variables, respectively

From: Development of a model for predicting the 4-year risk of symptomatic knee osteoarthritis in China: a longitudinal cohort study

Characteristics Number of imputed data points Total (N = 8193) No symptomatic KOA (N = 7378) Symptomatic KOA (N = 815) P
Age, mean (SD) years 0 58.82 (9.01) 58.73 (9.06) 59.60 (8.45) < 0.01
Sex 0     < 0.01
 Male   3942 (48.11) 3664 (49.66) 278 (34.11)  
 Female   4251 (51.89) 3714 (50.34) 537 (65.89)  
BMI, mean (SD) kg/m2 0 23.46 (3.49) 23.44 (3.47) 23.47 (3.48) 0.805
Waist circumference, mean (SD) cm 0 85.31 (9.58) 85.34 (9.54) 85.12 (9.56) 0.521
Residence area 0     < 0.01
 Rural, %   5406 (65.98) 4816 (65.28) 590 (72.39)  
 Urban, %   2787 (34.02) 2562 (34.72) 225 (27.61)  
Smoke behavior 40     < 0.01
 No smoking, %   4945 (60.36) 4374 (59.28) 571 (70.06)  
 Ex-smoking, %   687 (8.39) 624 (8.46) 63 (7.73)  
 Current smoking, %   2561 (31.26) 2380 (32.26) 181 (22.21)  
ADL/IADL difficulty 16     < 0.01
 No, %   6283 (76.69) 5787 (78.44) 496 (60.86)  
 Yes, %   1910 (23.31) 1591 (21.56) 319 (39.14)  
MS 1312     0.708
 No, %   6794 (82.92) 6122 (82.98) 672 (82.45)  
 Yes, %   1399 (17.08) 1256 (17.02) 143 (17.55)  
Hip fracture 72     < 0.01
 No, %   7941 (96.92) 7167 (97.14) 774 (94.97)  
 Yes, %   252 (3.08) 211 (2.86) 41 (5.03)  
Depression 1427     < 0.01
 No, %   6132 (74.84) 5702 (77.28) 430 (52.76)  
 Mild, %   1896 (23.14) 1561 (21.16) 335 (41.1)  
 Moderate-to-severe, %   165 (2.01) 115 (1.56) 50 (6.13)  
Comorbidities 0     < 0.01
 None, %   3778 (46.11) 3498 (47.41) 280 (34.36)  
 1~2, %   3659 (44.66) 3253 (44.09) 406 (49.82)  
 ≥ 3, %   756 (9.23) 627 (8.5) 129 (15.83)  
Health status 3     < 0.01
 Very good, %   289 (3.53) 278 (3.77) 8 (0.98)  
 Good, %   1075 (13.12) 1037 (14.06) 38 (4.66)  
 Fair, %   2752 (33.59) 2538 (34.4) 214 (26.26)  
 Poor, %   2957 (36.09) 2607 (35.33) 350 (42.94)  
 Very poor, %   1120 (13.67) 915 (12.4) 205 (25.15)  
Physical Activity Score      
 VPA score 4743     0.507
  No PA, %   4942 (60.32) 4462 (60.48) 480 (58.9)  
  Low level, %   590 (7.20) 524 (7.1) 66 (8.1)  
  Middle-to-high level, %   2661 (32.48) 2392 (32.42) 269 (33.01)  
 MPA score 4750     < 0.01
  No PA, %   3192 (38.96) 2914 (39.5) 278 (34.11)  
  Low level, %   891 (10.88) 798 (10.82) 93 (11.41)  
  Middle-to-high level, %   4110 (50.16) 3666 (49.69) 444 (54.48)  
 LPA score 4751     0.842
  No PA, %   1586 (19.36) 1431 (19.4) 155 (19.02)  
  Low level, %   1389 (16.95) 1245 (16.87) 144 (17.67)  
  Middle-to-high level, %   5218 (63.69) 4702 (63.73) 516 (63.31)  
  1. ADL, activities of daily living, BMI body mass index, IADL instrumental activities of daily living, LPA light physical activity, MPA moderate physical activity, MS metabolic syndrome, PA physical activity, SD standard deviation, VPA vigorous physical activity