Factors associated with low bone mineral density at diagnosis in pediatric Crohn's disease: a large retrospective cohort study.

BACKGROUND: Crohn’s disease can adversely affect bone mineral density and low bone mineral density is a concern in pediatric Crohn’s disease. We evaluated factors associated with below-average bone mineral density (z-score ≤ − 1.0) at Crohn’s disease diagnosis. METHODS: We retrospectively analyzed patients < 19 years diagnosed with Crohn’s disease at a single center. All patients underwent dual-energy x-ray absorptiometry at diagnosis. Lumbar spine (L1–L4) z-scores were used and below-average bone mineral density was defined as z–score ≤ − 1.0. Growth delay was defined according to the Paris classification. RESULTS: A total of 575 patients were analyzed and 27.2% had below-average bone mineral density. Compared with those with z–score > − 1.0, children with z–score ≤ − 1.0 were more often female, had lower hematocrit and weight/height/body mass index z-scores, higher Pediatric Crohn’s Disease Activity Index at diagnosis, and more frequent growth delay (all P < 0.05). Lower weight z-score (OR 0.465, P < 0.001) and growth delay (OR 1.846, P 0.011) were independently associated with below-average bone mineral density. CONCLUSIONS: Lower weight z-score and growth delay are independently linked to below-average bone mineral density at Crohn’s disease diagnosis. These findings highlight the importance of evaluating bone mineral density at diagnosis and closely monitoring patients with these risk factors.