Research Article

Radiation May Indirectly Impair Growth Resulting in Reduced Standing Height via Subclinical Inflammation in Atomic-Bomb Survivors Exposed at Young Ages

Table 4

Dose effect on inflammation (infl.), inflammation effect on height (ht.), indirect dose effect on height via inflammation, direct dose effect on height, total dose effect on height, and mediation proportion (MP) by sex and by age at exposure groups (standard error is the bootstrap standard error with 1,000 resamplings).

EffectsAge ATB group (year)
0–56–1718–240–17All: 0–24

Both sexes
5321,7721,0232,3043,327
Dose effect on infl.(a)1.933 (0.443; <0.001)0.917 (0.294; 0.002)0.687 (0.453; 0.129)1.206 (0.254; <0.001)1.086 (0.214; <0.001)
Infl. effect on ht.(b)−0.069 (0.029; 0.018)−0.025 (0.017; 0.141)−0.016 (0.020; 0.430)−0.038 (0.016; 0.018)−0.035 (0.012; 0.004)
Indirect dose effect(c)−0.134 (0.067; 0.047)−0.023 (0.018; 0.218)−0.011 (0.019; 0.566)−0.045 (0.023; 0.044)−0.038 (0.015; 0.015)
Direct dose effect(d)−1.126 (0.319; <0.001)−0.648 (0.173; <0.001)−0.324 (0.240; 0.176)−0.779 (0.157; <0.001)−0.663 (0.133; <0.001)
Total dose effect(e)−1.260 (0.326; <0.001)−0.671 (0.171; <0.001)−0.335 (0.240; 0.162)−0.825 (0.156; <0.001)−0.701 (0.133; <0.001)
MP(f) (%) (95% CI)(g)10.6% (−1.1, 22.4%)3.4% (−2.1, 9.0%)3.3% (−8.8, 15.3%)5.5% (−0.4, 11.3%)5.4% (0.8, 10.1%)

Males
2277042129311,143
Dose effect on infl.1.906 (0.592; 0.001)1.352 (0.425; 0.001)−0.183 (1.002; 0.855)1.514 (0.347; <0.001)1.311 (0.317; <0.001)
Infl. effect on ht.−0.003 (0.060; 0.955)−0.036 (0.031; 0.250)0.000 (0.041; 0.992)−0.032 (0.029; 0.271)−0.027 (0.023; 0.243)
Indirect dose effect−0.006 (0.123; 0.958)−0.049 (0.049; 0.314)0.000 (0.043; 0.999)−0.049 (0.048; 0.313)−0.036 (0.033; 0.281)
Direct dose effect −0.943 (0.513; 0.066)−0.681 (0.256; 0.008)0.034 (0.583; 0.953)−0.725 (0.226; 0.001)−0.622 (0.221; 0.005)
Total dose effect−0.949 (0.509; 0.062)−0.729 (0.252; 0.004)0.035 (0.581; 0.953)−0.774 (0.223; 0.001)−0.658 (0.219; 0.003)
MP (%) (95% CI)0.6% (−24.8, 26.0%)6.7% (−7.2, 20.7%)0.00% (—, —%)6.3% (−6.3, 19.0%)5.5% (−5.0, 15.9%)

Females
3051,0688111,3732,184
Dose effect on infl.1.987 (0.652; 0.002)0.457 (0.409; 0.263)0.850 (0.505; 0.092)0.852 (0.337; 0.011)0.858 (0.279; 0.002)
Infl. effect on ht.−0.105 (0.035; 0.003)−0.016 (0.019; 0.391)−0.022 (0.023; 0.338)−0.040 (0.016; 0.013)−0.037 (0.013; 0.006)
Indirect dose effect−0.209 (0.083; 0.012)−0.007 (0.015; 0.611)−0.018 (0.026; 0.472)−0.034 (0.020; 0.093)−0.032 (0.016; 0.049)
Direct dose effect−1.311 (0.395; 0.001)−0.601 (0.223; 0.007)−0.404 (0.255; 0.113)−0.832 (0.206; <0.001)−0.696 (0.165; <0.001)
Total dose effect−1.520 (0.414; <0.001)−0.609 (0.222; 0.006)−0.422 (0.255; 0.098)−0.866 (0.208; <0.001)−0.728 (0.166; <0.001)
MP (%) (95% CI)13.8% (0.8, 26.7%)1.1% (−3.7, 6.0%)4.3% (−8.8, 17.4 %)3.9% (−1.0, 8.8%)4.4% (−0.3, 9.1%)

Effect of radiation dose on inflammation (unit per Gy) with standard error (SE) and two-sided value in parenthesis; effect of inflammation index on height (cm per unit) with SE and two-sided value; indirect dose effect on height (cm/Gy) = (Dose effect on infl.) × (Infl. effect on height) with SE and two-sided value; direct dose effect on height (cm/Gy) with SE and two-sided value; total dose effect on height (cm/Gy) = direct dose effect (cm/Gy) + indirect dose effect (cm/Gy), with SE and two-sided value; mediation proportion (MP) = (indirect dose effect)/(total dose effect) (%); approximate 95% confidence interval (CI) for the mediation proportion using the first order approximation for standard error, , where and are total and indirect dose effects on height with standard errors and , respectively.