Unadjusted coefficient | 95% CI | p-value | Adjusted coefficient^{#} | 95% CI | p-value | |

Intercept | −0.60 | −0.73 – −0.47 | <0.001 | −0.85 | −1.08 – −0.62 | <0.001 |

Time | −0.06 | −0.09 – −0.05 | <0.001* | −0.08 | −0.11 – −0.05 | <0.001* |

CFTR modulator | 0.003 | −0.15–0.15 | 0.959 | 0.05 | −0.10–0.19 | 0.537 |

Time : CFTR modulator | 0.13 | 0.05–0.21 | 0.002* | 0.14 | 0.06–0.22 | <0.001* |

Interpretation: the intercept represents the mean BMI Z-score at the time of CFTR modulator initiation (baseline) in children under 19 years (according to World Health Organization growth reference standards). The coefficient of time indicates the mean annual change in BMI Z-score in the years before modulator initiation. The coefficient of CFTR modulator reflects the acute change in BMI Z-score after modulator initiation, whereas time : CFTR modulator represents the change in annual BMI Z-score in the years after CFTR modulator initiation compared to the years before. BMI: body mass index. CFTR: cystic fibrosis transmembrane conductance regulator. ^{#}: coefficients were adjusted for the main effects of sex, age at baseline, the interaction effect of sex with time and the interaction effect of age at baseline with time; *: significance level p<0.05.