Changes in Stress-Strain Index in School-Aged Children: A 3-Year Longitudinal Study
Table 1
The characteristics of the 217 participants at baseline and during the 3-year follow-up.
Parameters
Total
Boys
Girls
Z
value
n = 217
n = 104
n = 113
SSI
Baseline
1 (0.91, 1.1)
0.98 (0.89, 1.08)
1.02 (0.94, 1.12)
−1.91
0.06
Follow-up
0.92 (0.83, 1.01)
0.93 (0.83, 1.01)
0.91 (0.84, 1.01)
−0.04
0.97
Change
−0.09 (−0.18, 0.01)
−0.07 (−0.16, 0.03)
−0.11 (−0.19, 0)
−1.89
0.06
SE
Baseline
0.88 (0.38, 1.25)
0.88 (0.38, 1.25)
0.88 (0.5, 1.25)
−0.10
0.92
Follow-up
−0.75 (−2.25, 0.13)
−0.56 (−2.01, 0.25)
−1 (−2.25, 0)
−1.48
0.14
Change
−1.63 (−2.5, −1)
−1.38 (−2.38, −0.75)
−1.88 (−2.63, −1.25)
−2.63
0.01
AL
Baseline
22.95 (22.49, 23.51)
23.29 (22.84, 23.8)
22.65 (22.37, 23.04)
−6.04
<0.001#
Follow-up
23.82 (23.3, 24.51)
24.07 (23.52, 24.77)
23.59 (23.16, 24.2)
−3.49
<0.001#
Change
0.82 (0.57, 1.18)
0.76 (0.46, 1.14)
0.95 (0.65, 1.24)
−2.72
0.01
Age
Baseline
8.1 (7.82, 8.39)
8.11 (7.81, 8.37)
8.09 (7.88, 8.41)
−0.52
0.60
Follow-up
11.02 (10.74, 11.31)
11.03 (10.74, 11.29)
11 (10.76, 11.32)
−0.44
0.66
Change
2.92 (2.92, 2.94)
2.93 (2.92, 2.94)
2.92 (2.92, 2.94)
−0.51
0.61
AL, axial length; SE, spherical equivalent; SSI, stress-strain index. #, value for comparison between boys and girls using a Mann–Whitney U test. for comparison between baseline and follow-up using a Wilcoxon test.
