Table 3 Summary of meta-analysis results.
Group | Studies, n | Samples, n | Model | WMD (95% CI) | P value | I2 value, (%) | P value | |
|---|---|---|---|---|---|---|---|---|
ALAD 1 | ALAD 2 | |||||||
Lead-exposed groupa | 11 | 3540 | 582 | 82.6 | < 0.001 | |||
Random-effects model | − 1.653 (− 4.656–1.349) | 0.280 | ||||||
Fixed-effects model | − 1.724 (− 2.828 to − 0.619) | 0.002 | ||||||
Latitude subgroup | ||||||||
Non-low latitude | 6 | 2640 | 400 | 62.1 | 0.015 | |||
Random-effects model | − 4.019 (− 6.466 to −1.573) | 0.001 | ||||||
Fixed-effects model | − 4.019 (− 5.357 to − 2.682) | < 0.001 | ||||||
Low latitude | 5 | 638 | 94 | 63.6 | 0.004 | |||
Random-effects model | 2.020 (− 2.660–6.700) | 0.398 | ||||||
Fixed-effects model | 3.215 (1.253–5.176) | 0.001 | ||||||
Sex subgroup | ||||||||
Both | 7 | 3017 | 456 | 70.9 | 0.001 | |||
Random-effects model | − 2.126 (− 5.173–0.921) | 0.171 | ||||||
Fixed-effects model | − 3.341 (− 4.696 to − 1.985) | < 0.001 | ||||||
Male | 5 | 523 | 126 | 86 | < 0.001 | |||
Random-effects model | − 1.607 (− 7.363–4.149) | 0.584 | ||||||
Fixed-effects model | 1.478 (− 0.429–3.386) | 0.129 | ||||||
Age subgroup | ||||||||
Children | 1 | 1136 | 142 | \ | \ | |||
Random-effects model | − 7.600 (− 10.189 to − 5.011) | < 0.001 | ||||||
Fixed-effects model | − 7.600 (− 10.189 to − 5.011) | < 0.001 | ||||||
Adult | 11 | 2404 | 440 | 75.4 | < 0.001 | |||
Random-effects model | − 0.971 (− 3.815–1.872) | 0.503 | ||||||
Fixed-effects model | − 0.416 (− 1.637–0.806) | 0.505 | ||||||
HWE subgroup | ||||||||
No | 2 | 1643 | 195 | 61.2 | 0.052 | |||
Random-effects model | − 5.372 (− 9.624 to − 1.120) | 0.013 | ||||||
Fixed-effects model | − 6.117 (− 8.185 to − 4.048) | < 0.001 | ||||||
Yes | 9 | 1897 | 387 | 78.3 | < 0.001 | |||
Random-effects model | − 0.233 (− 3.460–2.994) | 0.887 | ||||||
Fixed-effects model | 0.030 (− 1.277–1.337) | 0.964 | ||||||
Non-Lead-exposed group | 20 | 10565 | 1438 | 99 | < 0.001 | |||
Random-effects model | − 0.113 (− 0.588–0.363) | 0.642 | ||||||
Fixed-effects model | − 0.837 (− 0.872 to − 0.801) | < 0.001 | ||||||
Latitude subgroup | ||||||||
Non-low latitude | 7 | 1909 | 361 | 79.6 | < 0.001 | |||
Random-effects model | 0.019 (− 0.195–0.233) | 0.862 | ||||||
Fixed-effects model | − 0.184 (− 0.230 to − 0.138) | < 0.001 | ||||||
Low latitude | 9 | 1738 | 219 | 85.9 | < 0.001 | |||
Random-effects model | − 0.819 (− 1.970–0.332) | 0.163 | ||||||
Fixed-effects model | − 1.981 (− 2.039 to − 1.922) | < 0.001 | ||||||
Unknow | 4 | 6918 | 858 | 0 | 0.627 | |||
Random-effects model | 0.110 (− 0.068–0.287) | 0.226 | ||||||
Fixed-effects model | 0.110 (− 0.068–0.287) | 0.226 | ||||||
Sex subgroup | ||||||||
Both | 14 | 8617 | 1054 | 99.2 | < 0.001 | |||
Random-effects model | − 0.152 (− 0.725–0.422) | 0.604 | ||||||
Fixed-effects model | − 0.864 (− 0.900 to − 0.829) | < 0.001 | ||||||
Male | 4 | 942 | 176 | 0 | ||||
Random-effects model | 0.349 (− 0.016–0.713) | 0.061 | ||||||
Fixed-effects model | 0.349 (− 0.016–0.713) | 0.061 | ||||||
Female | 4 | 1006 | 208 | 90.3 | < 0.001 | |||
Random-effects model | − 0.567 (− 2.035–0.901) | 0.449 | ||||||
Fixed-effects model | 0.411 (0.096–0.726) | 0.011 | ||||||
Age subgroup | ||||||||
Children | 5 | 1483 | 190 | 99.7 | < 0.001 | |||
Random-effects model | − 0.382 (− 1.361–0.597) | 0.445 | ||||||
Fixed-effects model | − 0.886 (− 0.922 to − 0.850) | < 0.001 | ||||||
Adult | 15 | 9082 | 1248 | 61.2 | < 0.001 | |||
Random-effects model | 0.043 (− 0.257–0.343) | 0.779 | ||||||
Fixed-effects model | 0.062 (− 0.093–0.218) | 0.431 | ||||||
HWE subgroup | ||||||||
Unknow | 1 | 313 | 57 | 0.0 | 0.357 | |||
Random-effects model | − 0.018 (− 0.298–0.262) | 0.901 | ||||||
Fixed-effects model | − 0.018 (− 0.298–0.262) | 0.901 | ||||||
Yes | 20 | 10312 | 1434 | 99.0 | < 0.001 | |||
Random-effects model | − 0.129 (− 0.633–0.376) | 0.617 | ||||||
Fixed-effects model | − 0.850 (− 0.886 to − 0.814) | < 0.001 | ||||||
Both | 1 | 1106 | 113 | \ | \ | |||
Random-effects model | − 1.700 (− 4.357–0.957) | 0.21 | ||||||
Fixed-effects model | − 1.700 (− 4.357–0.957) | 0.21 | ||||||
All | 27 | 15211 | 2133 | 98.4 | < 0.001 | |||
Random-effects model | − 0.318 (− 0.766–0.130) | 0.165 | ||||||
Fixed-effects model | − 0.838 (− 0.873 to − 0.802) | < 0.001 | ||||||
