Longitudinal changes in bone mineral density in children with inflammatory bowel diseases

Aim Children with inflammatory bowel disease (IBD) are prone to low bone mineral density (BMD). Our aim was to assess longitudinal changes in BMD in this population. Methods A retrospective longitudinal study of children with IBD, treated at two tertiary centres in Israel, who underwent two BMD measurements by dual-energy X-ray absorptiometry (DXA). Changes in lumbar spine BMD ( increment L1-4 z-scores) were examined for correlations with clinical characteristics. Results The cohort included 41 patients (age at diagnosis 12.1 +/- 3.5 years, 23 females).The mean interval between the scans was 3.4 +/- 2.0 years. There was a trend towards improvement in L1-4 z-scores (-1.64 +/- 1.02 vs -1.45 +/- 0.83, P = .12). increment L1-4 z-scores correlated positively with increment weight-standard deviation scores (SDS), increment height-SDS and increment BMI-SDS, and with age at the second scan (R = .55, P R = .42, P R = .42, P = .01; R = .35, P = .02, respectively); and negatively with L1-4 z-scores at the first scan (R = -.63, P < .01). Stepwise linear regression analysis identified the first scan L1-4 z-scores and increment weight-SDS as independent predictors of increment L1-4 z-scores. An L1-4 z-score <=-2 at the first DXA scan was associated with significant improvement at the second scan. Conclusion Improvement in BMD was more pronounced in children who gained weight or whose BMD was low at the first scan.