Sex Differences in Growth Recovery among Children with Crohn's Disease.

Background/Aims: Growth impairment remains a major concern in pediatric Crohn's disease (pCD) patients, yet long-term growth trajectories and sex-specific treatment responses have not been adequately characterized. Methods: This study investigated 2-year growth trajectories and determinants of catch-up growth from a nationwide registry in Korea. Growth outcomes were analyzed in 533 children with pCD using multivariable linear regression and generalized additive models (GAM). Results: At diagnosis, 16.1% and 4.1% of patients had weight-for-age and height-for-age z-scores less than -2, respectively. Weight recovery was more readily achieved than linear growth during follow-up (median z-score change: 0.61, p<0.001 vs -0.01, p=0.582). Females presented with lower baseline weight z-scores than males (-1.00 vs -0.63; p=0.001) but displayed superior weight recovery (0.81 vs 0.51; p<0.001) and significant height recovery (0.09 vs -0.08 in males; p<0.001). In the multivariable analysis, the baseline weight z-score, platelet count, albumin, and disease activity predicted weight recovery (R²=26.3%), while the baseline height z-score was the strongest predictor of height recovery. The GAM analysis suggested that infliximab use was associated with enhanced height recovery (β=0.104, p=0.045), with benefits observed primarily in females aged <14 years (β=0.339, p=0.044). Conclusions: This Asian cohort study with the largest population to date demonstrates that weight recovery precedes linear growth, with females showing superior catch-up. Notably, our findings highlight a selective association between infliximab treatment and height recovery in females younger than 14 years, suggesting sex- and age-specific differences in the treatment response that warrant further investigation. (Clinical trial registration: Korea Clinical Research Information Service KCT0008723).