Familial resemblance of bone mineral density in children with inflammatory bowel disease

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.

Choose your mother wisely: the familial resemblance of bone adaptation

This study demonstrates how complex bone microarchitectural features can be summarized to describe bone adaptations seen with aging in women, which are consistent with the stages of osteoporosis. Additionally, we showed familial resemblance in these bone microarchitectural traits between mothers and daughters that can be used to predict bone adaptations.

INTRODUCTION

Patient-specific characterization of bone quality can reduce complex microarchitectural features to common combinations of bone characteristics, known as bone phenotypes. This study investigated whether there is a general trend in bone phenotype change over time seen with aging in females and whether there is a familial resemblance to phenotype membership between mothers and daughters.

METHODS

Bone phenotype membership was calculated on biological mother and daughter pairs (Participants = 101), scanned using high resolution peripheral quantitative computed tomography, to the three pre-defined phenotypes (healthy, low volume, and low density). The trajectory of bone phenotype with age was explored using all participant's data. Linear regression models were used to assess the familial resemblance of phenotyping in the mother-daughter pairs.

RESULTS

When stratified for age, the trajectory of the phenotype membership transitioned from healthy (20-40 years), to low volume (40-60 years), to low density (60-80 years), which similarly aligns with the stages of osteoporosis observed in females. Familial resemblance (½h2) was observed in the healthy phenotype (β = 0.432, p < 0.01). Predictive modelling showed a significant association in phenotype membership between mothers and daughters in the healthy (R2 = 0.347, p = 0.04) and low volume (R2 = 0.416, p < 0.01) phenotypes, adjusted for age, height, and weight.

CONCLUSION

Our results suggest that phenotype membership in females changes with age in a pattern that is consistent with the stages of osteoporosis. Additionally, we showed familial resemblance in bone phenotype, which can be used to predict bone adaptations between mothers and daughters that are associated with bone loss with aging.

Bone Mass Development from Childhood into Young Adulthood in Patients with Childhood-onset Inflammatory Bowel Disease

BACKGROUND

Children who have inflammatory bowel disease (IBD) have increased risk of low bone mineral density (BMD). There is a scarcity of information on BMD development through puberty and into young adulthood in patients with childhood-onset IBD.

METHODS

We conducted a prospective longitudinal study of BMD in patients with childhood-onset IBD. In total, 74 children with IBD were followed into young adulthood, with a mean follow-up of 8.4 years. The BMD was assessed longitudinally using dual-energy X-ray absorptiometry of the lumbar spine, total hip and whole body, and related to anthropometric measures.

RESULTS

Young adult male patients with IBD had lower mean BMD Z-scores for the lumbar spine at -0.8 (±1.1 SD) and total hip at -0.5 (±0.9 SD), as compared to standard references. In young female patients, the BMD Z-scores were within the normal range at all 3 measured sites as compared to the standard references. There were no significant differences in the BMD Z-scores between patients with Crohn's disease and patients with ulcerative colitis. The female and male patients showed significantly improved mean lumbar spine BMD Z-scores during follow-up into young adulthood, indicating that bone accumulation in the lumbar spine continues beyond the expected age for achieving peak bone mass.

CONCLUSIONS

Male patients with childhood-onset IBD seem to have an increased risk of compromised BMD in young adulthood. Both female and male patients with IBD seem to increase their BMD beyond the age for expected peak bone mass (see Video abstract, Supplemental Digital Content 1, http://links.lww.com/IBD/B648).