Table 5.
Interaction between alpha- and gamma-tocopherol on 2-year wheezing
Univariate analysis: Distribution of alpha-tocopherol concentrations by 2-year wheezing status in subjects with low, medium, and high gamma-tocopherol concentrations (tertiles) | ||||
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Gamma-tocopherol concentration (tertiles, ng/mg creatinine) |
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Low | Medium | High | ||
Alpha-tocopherol concentration (ng/mg creatinine) [IQR] | No wheezing | 49 [36,74] | 73 [55,98] | 106 [83,123] |
Alpha-tocopherol concentration (ng/mg creatinine) [IQR] | Wheezing | 42 [26,53] | 67 [45,82] | 107 [87,121] |
P value | 0.004 | 0.059 | 0.42 | |
Multivariable regression analysis: The protective association of alpha-tocopherol with 2-year wheezing outcome differs by gamma-tocopherol level | ||||
Gamma-tocopherol concentration (tertiles, ng/mg creatinine) |
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Low | Medium | High | ||
Unadjusted ORs* | 0.51 (0.32,0.80) | 0.54 (0.28,1.05) | 1.64 (0.71,3.81) | |
Alpha-tocopherol concentration (ng/mg creatinine) IQR difference | aORs* | 0.49 (0.30,0.80) | 0.59 (0.29,1.18) | 1.65 (0.67,4.01) |
ORs were estimated for the association of alpha tocopherol with 2-year wheezing in low, medium, and high tertiles of gamma-tocopherol. Multivariable logistic regression was used for the adjusted association including infant sex, race, birth weight, breastfeeding status, maternal smoking during pregnancy, maternal asthma, and insurance status. P interaction (likelihood ratio test) cross-product alpha (continuous)—and gamma-tocopherol tertiles = 0.05. Alpha-tocopherol was natural log transformed.