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Table 7 Basic scenarios without confounding with nonlinear GA effect on BW

From: On the use of the outcome variable “small for gestational age” when gestational age is a potential mediator: a maternal asthma perspective

Scenario
(model, interpretation of effect)
mean se null ICS effect?
Basic 1 (M1, total) −0.2921 0.2050 yes
Basic 1 (M2, direct) −0.0693 0.1479 yes
Basic 1 (\( {M}_2^{\ast } \), direct) −0.0137 0.1442 yes
Basic 1 (M3, total) 0.0049 0.0026 yes
Basic 1 (M4, direct) −0.0008 0.0015 yes
Basic 2 (M1, total) −359.88 0.2132 no
Basic 2 (M2, direct) 40.140 0.1773 no
Basic 2 (\( {M}_2^{\ast } \), direct) −0.0502 0.1856 yes
Basic 2 (M3, total) 1.3082 0.0021 no
Basic 2 (M4, direct) −0.0008 0.0015 yes
Basic 3 (M1, total) −100.29 0.2050 no
Basic 3 (M2, direct) −100.07 0.1479 no
Basic 3 (\( {M}_2^{\ast } \), direct) −100.01 0.1442 no
Basic 3 (M3, total) 0.2730 0.0024 no
Basic 3 (M4, direct) 0.5611 0.0014 no
Basic 4 (M1, total) −459.88 0.2132 no
Basic 4 (M2, direct) −59.860 0.1773 no
Basic 4 (\( {M}_2^{\ast } \), direct) −100.05 0.1856 no
Basic 4 (M3, total) 1.6259 0.0020 no
Basic 4 (M4, direct) 0.5611 0.0014 no
  1. Legend. Mean of the estimated exposure (ICS) effect (mean difference or log odds ratio) on the outcome (BW, LBW or SGA) based on 1000 samples of size 20,000, with Monte Carlo standard error (se)
  2. Basic Scenario 1: no ICS effect on BW; Basic Scenario 2: indirect ICS effect on BW;
  3. Basic Scenario 3: direct ICS effect on BW; Basic Scenario 4: direct and indirect ICS effect on BW
  4. M1: BW ~ ICS; M2: BW ~ ICS + GA; \( {M}_2^{\ast } \): BW ~ ICS + GA + GA2 + GA3; M3: LBW ~ ICS; M4: SGA ~ ICS;
  5. null ICS effect = yes if 0 mean ± 1.96se
  6. Abbreviations: BW birth weight, GA gestational age, ICS inhaled corticosteroids, LBW low birth weight, SGA small for gestational age