Prevalence and predictors of low bone mineral density in pediatric inflammatory bowel disease.

OBJECTIVES

Bone health is at risk in children with inflammatory bowel disease (IBD). This study examined the prevalence and predictors of low bone mineral density (BMD) in a cohort of children and young adults with IBD.

METHODS

This single-center retrospective study included patients with IBD, ages 3.5-22 years, with completed dual x-ray absorptiometry (DXA) scans from 2006 to 2019. Demographic, clinical, and laboratory data were collected. Logistic regression analysis identified predictors associated with low BMD (Z-scores ≤ -2 standard deviations [SDs]) for three outcomes. In an overlapping IBD cohort with available genetic data between 2002 and 2019 (n = 378), genetic risk for diminished bone health was calculated using published polygenic risk scores generated from genome-wide association studies based on DXA or heel ultrasound speed of sound (SOS). Linear regression analysis examined associations of low BMD and genetic risk.

RESULTS

Low BMD prevalence was 7% in our cohort (n = 600) based on spine bone mineral apparent density (BMAD), which best accounts for growth delays. Median (interquartile range [IQR]) spine BMAD Z-score was -0.37 SD (-1.11 to 0.35). Predictors of low BMAD included lower BMI Z-score (odds ratio [OR]: 0.67, p value: 0.02) and decreased height Z-score (OR: 0.6, p value: 0.005). Of those with longitudinal data (n = 118), low BMI (OR: 0.44, p value: <0.001) and steroid use (OR: 3.42, p value: 0.01) were associated with suboptimal bone health (Z-scores ≤ -1SD). In the cohort with genetic data, heel genomic SOS (β [standard error] = 0.17 [0.35], p ≤ 0.01) was associated with BMD.

CONCLUSIONS

Lower BMI should prompt DXA monitoring in pediatric IBD. Genetic predisposition may identify an at-risk subpopulation.