Table 2 Baseline characteristics of the subjects (n = 12,766)
Variable | All | Grade 1 | Grade 2 | Grade 3 | F/X2 | P |
|---|---|---|---|---|---|---|
number | 12,766 | 4509 | 4034 | 4223 | ||
age | 8.30 ± 0.94 | 7.31 ± 0.46 | 8.41 ± 0.49 | 9.26 ± 0.45 | 19382.45 | <0.001 |
Male (%) | 7252 (56.80) | 2621 (58.1) | 2399 (56.8) | 2232 (55.3) | 6.796 | 0.033 |
height (cm) | 130.95 ± 9.54 | 124.58 ± 8.33 | 131.70 ± 7.77 | 137.05 ± 7.89 | 2666.47 | <0.001 |
weight (kg) | 27.01 ± 7.36 | 24.50 ± 5.65 | 26.67 ± 6.71 | 30.03 ± 8.42 | 688.84 | <0.001 |
BMI (kg·m-2) | 15.71 ± 3.55 | 15.37 ± 3.49 | 15.79 ± 3.21 | 15.93 ± 3.92 | 28.17 | <0.001 |
SE (D) | -0.17 (-0.28, 0.11) | 0.20 (0.11, 0.27) | -0.14 (-0.21, 0.06) | -0.29 (-0.37, -0.22) | 1253.37 | < 0.001 |
Number of myopia (%) | 3074 (24.08) | 792 (17.56) | 843 (20.90) | 1439 (34.08) | 1169.77 | <0.001 |